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DIY Bundle

and HDD Kit for 21.5" iMac (2012 and later)

Mac / USB 3.0
Mercury SSD and iMac HDD Kit
Everything You Need!
The complete solution for your 2012 and later 21.5" iMac
Experience the extreme performance of an OWC SSD upgrade with this easy DIY SSD and hard drive replacement kit. Add an SSD to your hard drive equipped iMac to experience faster booting, near instant application launches and data transfer speeds up over 500 MB/s.
Fast and reliable solid-state storage
With sustained data speeds of over 500 MB/s, up to 100X greater data protection than enterprise class Hard Disk Drives, and RAISE technology for RAID like data protection and reliability, the OWC Mercury 6G SSD line delivers unbeatable performance, that's backed by an incredible OWC SSD Limited Warranty.
A True DIY upgrade
This comprehensive kit has all the tools you need to replace your factory HDD with a high performance SSD, bringing a complete diy upgrade within your reach. Includes drivers, glass removal suction cups, and screen adhesive so you can get the job done yourself. The included OWC Express 2.5" USB 3.0 enclosure offers maximum mobile data storage/backup potential with a sleek, totally bus powered design. Just add your iMac's factory 2.5" hard drive or SSD and take your digital life with you wherever you roam!

Please note, that before attempting to perform this installation, it is recommended you watch the associated instructional video in its entirety to determine your ability to perform this complex procedure. OWC assumes no responsibility for damage that may occur during the install.

Release Candidate (RC) firmware set

There are two kinds of firmware for SSDs Mass Production (MP) and Release Candidate (RC). Prior to an MP firmware release, there are beta firmware releases and an RC firmware release. Often, the RC is the same as the MP release, however there can be small changes and bug fixes made between the two. OWC has evaluated the RC for the 6Gb/s SandForce 2281 Processor and found it to be stable with no issues reported during our testing. However, as with any evolutionary product, issues may surface as different usages and configurations are employed and it is important to understand that there will be further updates and revisions.

Since no firmware update is currently offered for the OWC Mercury EXTREME Pro 6G SSD, no update page exists. To see the typical steps involved with a self performed field firmware update, please visit our 3Gb/s product update page at: http://eshop.macsales.com/Customized_Pages/Framework.cfm?page=sf_firmware.html

It is important to note that the current firmware update tool requires the use of Windows XP/Vista/7. OWC is currently working on a Mac OS based update tool, but we do not have an exact availability date.

960GB Mercury Extreme Pro 6G SSD Specifications:


Phison PS3112-S12 with 7% over-provisioning
Synchronous Triple-Level Cell (TLC) 3D NAND Flash
Form Factor
2.5-inch 7mm
SATA 6.0 Gb/s
960GB useable capacity
Total Flash Memory Components – 1024GB
64GB allocated to real-time data redundancy & error correction
Formatted Capacity
RAID Support
SMART Attributes
Standard attributes supported
Native Command Queuing
up to 32 commands
Manufacturer Model Number
RoHS Compliant


Height (max)
0.7 cm (0.3 in)
OWC 7mm – 9.5mm Adapter
1 included (buy additional)
Width (max)
7.0 cm (2.8 in)
Length (max)
10.0 cm (3.9 in)
77.0 g (0.17 lbs)


Data Reliability
Built-in BCH ECC: Up to 66 bits correctable per 1024 bytes
Nonrecoverable Read Errors
Less than 1 sector per 1016 bits read


Sequential Reads (Max)
Up to 550 MB/s
Sequential Writes (Max)
Up to 530 MB/s
Sequential 4K Read
Up to 100,000 IOPS
Sequential 4K Write
Up to 90,000 IOPS


Write: 2000mW (2.0W) Maximum draw

Environmental (Operating)

-304.8 m to 3,048.0 m (-1,000 ft to 10,000 ft)
Temperature (°F)
32°F to 158°F
Temperature (°C)
0°C to 70°C

Environmental (Non-Operating)

304.8 m to 12,192.0 m (-1,000 ft to 40,000 ft)
Temperature (°F)
-40°F to 185°F
Temperature (°C)
-40°C to 85°C


Idle (Typical)
0.0 bels
Seek (Typical)
0.0 bels
  • 1GB = 1,000,000,000 bytes. Total accessible capacity varies depending upon operating environment (typically 5-10% less). The actual total capacity will depend on your own defined file settings/preferences. 
  • In terms of standard gigabytes, 1GiB ≈ 1.074GB and refers to the actual formatted capacity of shown under Mac OS 10.5 or earlier and Microsoft Windows OS.

Express Enclosure Specifications:

OWC Part Number

  • ES2.5BU3S

Software Requirements

  • OS
    • Mac OS 8.6 or later
    • OS X 10.2 or later
    • Windows 98 or later
  • Driver
    • Driver not required

Hardware Requirements

  • Minimum
    • Mac or PC featuring USB 1.1 interface
  • Recommended (Best Performance)
    • Mac or PC featuring USB 3.0 interface

Interface (Chipset)

  • (1) USB 3.0 (ASMedia ASM1053E)

Drives Supported

  • (1) 2.5" SATA 6Gb/s drives
    • SATA revision 3.0 (6Gb/s) compliant
    • Compatible with SATA revisions 2.0 (3Gb/s) and 1.0 (1.5Gb/s)

Power Supply

  • Bus Power via USB


  • Height: 0.6 in (1.5 cm)
  • Width: 3.1 in (7.9cm)
  • Length: 5.1 in (13.0 cm)


  • Without Drive: 2.0 oz (56 g)

Operating Environment

  • Dependent on mechanism installed
Manufacturer provided specifications for Other World Computing p/n K21IM12HP1TB UPC#: 812437028966


Install Video

This product is compatible with... Learn how to find your Mac's model ID
iMac Intel
iMac w/Retina 4K display
(21.5-inch Early 2019)
(March 2019)
Model ID:iMac19,2
3.6GHz i3, 3.0GHz i5, 3.2GHz i7
iMac Intel
iMac w/Retina 4K display
(21.5-inch Mid 2017)
(June 2017)
Model ID:iMac18,2
3.0GHz i5, 3.4GHz i5, 3.6GHz i7
iMac Intel
iMac (21.5-inch Mid 2017)
(June 2017)
Model ID:iMac18,1
2.3GHz i5
iMac Intel
iMac w/ Retina 4K display (21.5-inch Late 2015)
(October 2015)
Model ID:iMac16,2
3.1GHz i5, 3.3GHz i7
iMac Intel
iMac (21.5-inch Late 2015)
(October 2015)
Model ID:iMac16,1
1.6GHz i5, 2.8GHz i5
iMac Intel
iMac (21.5-inch Mid 2014)
(June 2014)
Model ID: iMac14,4
1.4GHz i5
iMac Intel
iMac (21.5-inch Late 2013)
(September 2013)
Model ID: iMac14,3
2.9GHz i5 or 3.1GHz i7
iMac Intel
iMac (21.5-inch Late 2013)
(September 2013)
Model ID: iMac14,1
2.7GHz i5
iMac Intel
iMac (21.5-inch Early 2013)
(March 2013)
Model ID: iMac13,1
3.3GHz i3
iMac Intel
iMac (21.5-inch Late 2012)
(October 2012)
Model ID: iMac13,1
2.7GHz i5 , 2.9GHz i5, 3.1GHz i7


  • (1) OWC Mercury Extreme Pro 6G SSD
  • (1) OWC Express enclosure - silver
  • (2) OWC 2-1/4" Suction Cup
  • (1) Torx T10 driver
  • (1) 21.5" iMac Adhesive tape set for proper display resealing
  • (1) Nylon Pry Tool (Spudger)
  • (1) OWC Screen Removal Tool
  • (1) OWC Blue Microfiber Screen Cleaning Cloth

NOTE: This kit contains consumable and/or one time use components and therefore is non-refundable if opened. If you have any concerns about your ability to perform the upgrade, you can return the unopened kit for a refund.


The best warranty is one you never have to use - but should the need occur - we're proud to provide a superior level of support and service coverage to our customers.

5 Year OWC SSD Limited Warranty

1 Year OWC Enclosure Limited Warranty

Even when not used, we understand the peace of mind afforded by a longer warranty period. OWC's industry leading coverage is a testament to our confidence in the reliability of the solutions that we offer. OWC solutions are engineered to demanding quality standards in order to deliver the most reliable, highest performance available on the market in each storage category.

Customer Ratings

Write a Review 5 / 5 9 out of 9 (100%) reviewers would recommend this product
Verified Buyer
Reviewer: ala02c Owned Product: less than a month
Rating: 5/5 The single best upgrade you can make. July 24, 2018 My 2012 iMac was dying a slow death. I work with audio and the sessions were running slower and slower with more frequent freezes and crashes. Looking for a solution, I ordered this kit.

Install was super easy. I watched the videos, followed the instructions, and with the help of a friend we had the whole thing installed in under 30 minutes.

The computer is crazy fast. Start up time is 15 seconds. It was over 90 seconds before... My workflow is completely improved, its like having a new computer. Thanks for making this amazing product. Great value and performs exactly as advertised.

I would recommend this item to a friend! Customer Videos:

Verified Buyer
Reviewer: Bugeyesprite Location: Tipton Iowa Age: 55-65 Experience Level: Power User Owned Product: less than a month
Rating: 5/5 Great install video and tools July 14, 2018 The 1 TB SSD is working well. The best part of purchasing from OWC is the install video and the tools that come with the install kit. This could have been a very difficult install, but I watched the video before starting and then watched it as I went. This gave me the confidence to do it. I took my time and was careful, and the install went very well with no problems. The SSD seemed expensive when comparing other drives, but I went with OWC for their support and their quality.

I would recommend this item to a friend! Customer Videos:

Verified Buyer
Reviewer: PCGuy
Rating: 5/5 Perfect June 30, 2018 Used this for my 21.5" iMac 14,4 (EMC 2805). Installed in about an hour. Kit includes everything you need. The external USB HDD enclosure made it simple to install OSX on the new SSD: just boot the computer from the external HDD (previously removed from the iMac) and use the Disk Utility to format and install OSX (downloaded from the App Store) on the internal SSD. I had no problems whatsoever installing the hardware or reinstalling the operating system. The glass removal was easier than I expected, but it is important to take your time and be patient with that process. Watch the instructional video included in the listing. Before reattaching the glass, plug everything in and make sure it powers on. The computer is like new now, much much MUCH faster with the new SSD!

I would recommend this item to a friend! This review is from DIY Kit for 2012 or later 21.5" iMac's factory HDD: 120GB OWC Mercury Extreme Pro 6G SSD.. Customer Videos:

Verified Buyer
Reviewer: FenderJedi Location: Bahrain Age: 55-65 Experience Level: Home User Owned Product: less than a month
Rating: 5/5 Fabulous service February 3, 2018 My 21.5in iMac was dying a death, the hard drive showing exceedingly slow transfer speeds. I had the option of taking it in for repair in Bahrain or having a go at fixing it myself, at task which I was not looking forward to at all. I did a Google search for replacing the drive and saw one or two YouTube videos that didn't exactly give me confidence to tackle it myself, especially the screen removal. Then I did a search for the drive itself. I knew I wanted an SSD and these guys were competitive on price AND would deliver to Bahrain which a lot of companies won't do. Not only that, but you can order the part with the confidence it will be the correct one by using the 'My upgrades' feature and selecting the correct model. They even have a video on how to change the drive and a kit to make it a really simple task. The order arrived on the third day, a record for getting anything to Bahrain. I set aside a whole day to tackle the change, but with the kit and instructions, I had the drive changed and the Mac back together in less than an hour, including vacuuming the dust from inside the case. If you are hesitating on whether to do this yourself, don't. It really is a task which can be carried out by anyone with a modicum of common sense, the ability follow instructions and is capable of using basic tools.

I would recommend this item to a friend! Customer Videos:

Verified Buyer
Reviewer: MacUser1982 Owned Product: 1-3 months
Rating: 5/5 Speed Speed Speed January 29, 2018 Fits perfectly, tools make its easy to install and increased the speed of my iMac 10 fold. Great product.

I would recommend this item to a friend! This review is from DIY Kit for 2012 or later 21.5" iMac's factory HDD: 240GB OWC Mercury Extreme Pro 6G SSD.. Customer Videos:

Verified Buyer
Reviewer: ITnewbie Location: FL Age: 55-65 Experience Level: Noob Owned Product: 1-3 months
Rating: 5/5 Great Customer Support - Even when my mistake January 21, 2018 I made a mistake while installing this kit and ruined the tape. I called Customer Support to find out about repurchasing just the tape. Even though I explained that it was my fault, after a brief hold, I was informed that they had a set of tapes they could send me free of cost. They were so awesome! Project completed with ease second time.

I would recommend this item to a friend! Customer Videos:

Verified Buyer
Reviewer: RayZColorado Location: Denver area Age: 55-65 Experience Level: IT Professional Owned Product: over 6 months
Rating: 5/5 Easy Install. Smokin' fast SSD January 20, 2018 It took me months to build up the courage to replace my iMac hard drive and in the meantime MacSales came up with a new (better) tool to release the monitor from the double-stick tape that holds it on. I was having trouble with the guitar pick though I'm sure it works. Anyway, last weekend having gathered up the courage, I used the how-to video from MacSales and I did it. And my iMac is now smokin' fast like I wished it had been all along. I highly recommend the drive and MacSales for great products, price and support. You guys rock.

I would recommend this item to a friend! Customer Videos:

Verified Buyer
Reviewer: FDiaz Location: Guatemala Age: 55-65 Experience Level: Power User Owned Product: over 6 months
Rating: 5/5 Great Purchase January 15, 2018 Very Happy with this purchase. Easy to install, and the overall performance of my iMac improved notoriously !!!

I would recommend this item to a friend! Customer Videos:

Verified Buyer
Reviewer: Archidad Age: 45-54 Experience Level: Power User Owned Product: less than a month
Rating: 5/5 Did what I needed at the right price. November 19, 2017 My review in 9 steps: 1. iMac late 2012 was driving me nuts with how slow it had become, partly due to the HDD being quite full, mostly due to HDD being slow. 2. I read around and found this kit recommended by others. 3. I bought the 1tb SSD kit, along with two 8gb memory modules (was going to be in there anyway, might as well update RAM). 4. Watched the installation video. This is a must. 5. Using the great tools provided, installed the SSD and the RAM 6. Checked all connections twice. Then again. Then I CAREFULLY re-adhered the screen. 7. Put the old HDD in the exterior drive case to use it for user accounts and photos. Struggled with moving user accounts to the HDD, but eventually got them moved. 8. Thrilled at the performance increase. Seriously, faster than when new. 9. Wrote this review. :)

I would recommend this item to a friend! Customer Videos:

Verified Buyer
Reviewer: ajsor Location: Lisbon, Portugal Age: 45-54 Experience Level: IT Professional Owned Product: 1-3 months
Rating: 5/5 very happy December 18, 2016 I am very happy for this seller. All works like a charme, no problem at all in anything. The kit itself was a magnificent idea. Thanks, AR

I would recommend this item to a friend! Customer Videos:

Verified Buyer
Reviewer: Kryl Location: Los Angeles, CA Age: 35-44 Experience Level: IT Professional Owned Product: 1-3 months
Rating: 5/5 Look into this before buying a new Mac! November 16, 2016 This is an easy and affordable way to breath new life into your older Apple products. It really is amazing how much the older clunky magnetic hard drive acts as a performance bottleneck. Replacing it with the OWC SSD kit has my iMac running faster than the day I brought it home. I spent the extra money when I originally bought this iMac so that I'd enjoy many years of service before having to replace it. This upgrade has made that a reality.

I would recommend this item to a friend! Customer Videos:

DIY Bundle 1.0TB OWC 6G SSD and HDD Kit for 21.5" iMac (2012 and later) Mfr P/N: K21IM12HP1TB OWC SKU: OWCK21IM12HP1TB Complete DIY kit for upgrading your late 2012 or later 21.5" iMac's hard drive 5 Year OWC Limited Warranty Ships: Same Day Only $286.86Bundle Priced for $228.75
Add to CartOther World Computing K21IM12HP1TB In Stock, Click to Buy Now
Additional Capacities:
  • 240GB
    • Ships: Same Day
    • Only $136.86
    • Bundle Priced for $133.75
  • 480GB
    • Ships: Same Day
    • Only $206.86
    • Bundle Priced for $144.64
  • 1.0TB
  • 2.0TB
    • Ships: Same Day
    • Only $498.87
    • Bundle Priced for $454.75