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OWC Mercury
On-The-Go® Pro

USB 3.0 & 2.0 Storage Solution

Mac / PC / USB 3.0 & 2.0
  • Mac
  • PC
  • USB 3.0
The OWC Mercury On-The-Go USB 3.0 & 2.0 Storage Solution provides maximum storage in an ultra-portable, totally bus powered design!
Stylishly engineered in a sleek, impact-resistant acrylic enclosure, the Mercury On-The-Go Pro incorporates shock-isolation technology to give maximum protection for your precious data inside. The Mercury On-The-Go Pro is a true must-have for users like you who are seeking High-Performance and Highly Reliable storage weighing less than 11 ounces and that is small enough to fit in your pocket.
Outstanding Features
Built with the fastest and most reliable Solid State Drive on the market today. The Mercury Electra 6G SSD line features industry leading SandForce® DuraClass Technologies:
  • DuraWrite™ extends the endurance of your Solid State Drive (SSD).
  • Intelligent Block Management & Wear Leveling automatically distributes data evenly across the entire SSD.
  • Intelligent Read Disturb Management spreads the active read/write across the flash components eliminating data corruption caused by constant use.
  • Intelligent "Recycling" for advanced free space management gradually re-writes data across the SSD over time to ensure data never gets corrupted.
  • RAISE™ (Redundant Array of Independent Silicon Elements) protects the data on your drive similar to having a RAID setup.
  • Best-in-Class ECC Protection for longest data retention and drive life.
Compact and Versatile
If you're looking for one of the most compatible mass storage solutions made, look no further! The OWC Mercury On-The-Go drive is all you'll need! The OWC Mercury On-The-Go has what it takes to truly work cross platform. The Mercury On-The-Go Pro is bus-powered, so it doesn't require an AC adapter!
Cool and Silent
The OWC Mercury On-The-Go's fanless design offers near silent operation while still keeping your drive cool. The built-in aluminum heatsink underneath the drive and passthrough cooling vents on the top of the case work in tandem to provide optimum results. 
SuperSpeed Ready, Yet Backward Compatible
The OWC Mercury On-The-Go can be used with any Macintosh or PC with a USB 3.0 & 2.0 port. Now you can have SuperSpeed performance up to 500MB/s and compatibility with legacy machines!


  • OWC Mercury On-The-Go Pro USB 3.0 & 2.0 storage solution
  • High Quality Double Shielded USB 3.0 & 2.0 certified connecting cable
  • Carrying Case
  • Assembly Manual & User Guide
  • OWC 3 Year Solution Warranty with 48-Hour Turnaround Time


Product Specifications:

Bus Interface

  • USB 3.0 & 2.0 Backwards compatible port.


  • ASMedia 1051e USB 3.0 chipset

Standard Mechanism

    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.

    250GB Mercury Electra 6G SSD Specifications:


    Form Factor
    Standard 7mm 2.5"
    SATA 6.0 Gb/s
    Capacity 1
    250GB Useable Capacity
    Total Flash Memory Components: 256GB
    6GB Allocated to real-time data redundancy and error correction
    Formatted Capacity1
    233 GiB
    RAID Support
    SMART Attributes
    Standard 2
    Native Command Queuing
    Up to 32 simultaneous commands
    RoHS Compliant
    Reach Certification


    Height (max)
    7 mm (0.276 in)
    Width (max)
    70.06 mm (2.758 in)
    Length (max)
    100.12 mm (3.941 in)
    60.0 g (0.13 lbs)


    MTBF (Mean Time Between Failures)
    1,500,000 hours
    ATA Security Feature Command Set and Password Login Support
    Error Correction
    Built-in ECC
    TRIM Support
    OS Dependent
    Wear Leveling
    Nonrecoverable Read Errors
    Less than 1 sector per 1015 bits read


    Mac OS Compatibility
    PC OS Compatibility
    Other Requirements
    Requires a Mac, PC, or drive enclosure with an available SATA drive bay. SATA III (6.0 Gb/s) required for best performance.


    Average Access Time
    <0.1 ms
    Sequential Read (Max)
    Sequential Write (Max)
    Random 4K Read
    Up to 54,000 IOPS
    Random 4K Write
    Up to 81,000 IOPS


    Active (Max)
    Idle Mode (Max)

    Environmental (Operating)

    1500 G max at 0.5 ms
    Temperature (°F)
    32°F to 158°F
    Temperature (°C)
    0°C to 70°C
    5% to 95% non-condensing

    Environmental (Non-Operating)

    1500 G max at 0.5 ms
    Temperature (°F)
    -40°F to 185°F
    Temperature (°C)
    -40°C to 85°C


    Idle (Typical)
    0.0 bels
    Seek (Typical)
    0.0 bels
    1. 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. 
    2. Temperature reporting is currently an unsupported feature because due to the operating characteristics of SSDs, it is highly unlikely one would ever exceed an OWC Mercury SSD's stated operating temperature ceiling of 158F/70C. However, we are looking into supporting this feature in the future via a firmware update. Firmware updates can be found here: http://eshop.macsales.com/tech_center/OWC/SSD.
  • 250GB* OWC Mercury Electra 6G SSD**

  • *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.

    **OWC reserves the right to replace or upgrade to equivalent or better components.

Drive Interface

  • SATA (Serial ATA) Revision 3.0

Max Data Transfer Rate

  • USB 3.0 – 500MB/s
  • USB 2.0 – 60MB/s

Port/Interface Bootability

  • Can I use this solution as an external startup drive?
  • USB 3.0: Supported on Macs and PC's meeting minimum requirements. - Click for more info
  • USB 2.0: Supported on Macs and PC's meeting minimum requirements. - Click for more info

UASP (USB Attached SCSI Protocol) Compliant

  • Yes


System Requirements

  • Macintosh: Macintosh OS 8.6 to 9.2.2, OS X 10.2.x or later including 'Mavericks' 10.9.x, and an available USB 3.0 port. Time Machine® Compatible: Mac OS X 10.5 (version introduced) and later.
  • PC: Windows Vista, XP, 2000, NT, 98, and an available USB 3.0 port.
  • Linux: Linux compatible via supported the USB interface.

Power Supply*

  • Bus power via USB on most computers with factory installed USB 2.0 or USB 3.0 port.
  • Optional AC Adapter* (available as a separate purchase here)

  • * AC adapter not required for most applications provided computer bus supplies appropriate power needs.

External Case Dimensions

  • 3.5" (W) x 5.5" (D) x 1" (H)
  • 88.9mm x 139.7mm x 25.4mm

Total Shipping Weight

  • 0.35lbs. (0.15kg)

User Guide

Recommended USB 3.0 Cards

Operating Environment:


  • (operating) 0°C – 70°C (32°F – 158°F)
  • (non-operating) -40°C – 85°C (-40°F – 185°F)

Relative Humidity

  • (operating) 8% – 90% RH (Non-condensing)
  • (non-operating) 5% – 95% RH (Non-condensing)


  • (operating) 1500G 0.5mS;
  • (non-operating) 1500G 0.5mS


  • (operating) 16G (16 – 1600Hz)
  • (non-operating) 16G (16 – 1600Hz)
Manufacturer provided specifications for Other World Computing p/n MSU3SSD240GB UPC#: 812437022599


Click any of the benchmarks below to view the results.
macOS Test Results
Windows Test Results


Customer Ratings

Write a Review 4.8 / 5 119 out of 128 (93%) reviewers would recommend this product
1 2 3 4 5 6
Verified Buyer
Reviewer: MountainMan Location: Woodland Park, CO Age: 55-65 Experience Level: Power User Owned Product: over 6 months
Rating: 5/5 Cheap and effective fire insurance July 3, 2012 I just purchased my fourth OWC Mercury On-The-Go USB drive. They have proven invaluable for sending back and forth to clients and photographers for large file transfers, as they are small and easy to use. This summer I found another use for them; the Colorado wildfires have posed a serious threat to property, mine included, so I videoed my entire home and its contents for insurance purposes. These large video files went directly upon the On-The-Go drive and to the safe deposit box at my bank. The small size of the drive makes this possible. I have probably 10TB of various OWC drives, and while there are cheaper drives on the market, they are no bargain if they fail. I've had excellent luck with all OWC storage products and will buy no others.

I would recommend this item to a friend! This review is from 500GB OWC Mercury On-The-Go Pro Portable Bus-Powered Solution with USB 3.1/3.0.

Verified Buyer
Reviewer: TonyB Location: Perth WA Age: 35-44 Experience Level: Power User Owned Product: less than a month
Rating: 3/5 Disappointing June 30, 2012 Having ripped out many a hard drive from all sorts of computers and also having set up plenty of portable bare hard drives I found this kit to be disappointing and difficult. The instructions are split into two separate documents neither of which fully cover the installation process. Normally this wouldn't be a problem because this kind of installation should be straightforward. However, the SSD hold down screw was too long such that it wouldn't firmly hold the SSD in place and the other screws were too short to hold the bridge card in. Luckily it seems to fit in quite snugly without any screws. But if the ultimate test is does it work? - Well yes. Is it blazingly fast? - No not really. With an OWC 500GB SSD in there it certainly doesn't achieve the 500MB/sec max speeds claimed for USB3.0 nor the 200MB/sec for the SSD. I transferred 150GB using USB3.0 in 31 minutes (which by my calculations is about 80 MB/sec). I did exactly the same test onto another brand's USB3.0 5400RPM SATA 2.5" HD and it took 46 minutes. Did the same onm a USB2.0 5400RPM SATA 2.5" HD and it took 66 minutes. So I guess there are speed advantages but in the order of two times and no more.

This review is from OWC Mercury On-The-Go USB 3.0 External Enclosure for Apple MacBook Air 2010 & 2011 Flash Storage.

Response from OWC, Marketing July 2, 2012 This product was meant as a temporary solution to getting some use from the removed Apple drive on your 2010-2011 MacBook Air while a more customized solution was in development. The Mercury Aura Pro Envoy is that customized solution: http://eshop.macsales.com/item/OWC/MAU3ENVOY/ The second instruction booklet is to show what is different for installation of the MacBook Air SSD as opposed to a 2.5" hard drive that the On-The-Go line was designed for: http://eshop.macsales.com/shop/firewire/on-the-go Transfer speeds will vary depending on your setup, our marketing simply states the fastest theoretical speeds of the interfaces. The top speed limitation is always the lowest common denominator. For example, while USB 3.0 has a maximum speed to 500MB/s - the fastest MacBook Air stock SSD we've seen has a maximum speed of 200MB/s (some models were slower), so right off the bat, the top speed can only hit 200MB/s if you have the fastest SSD. Now, let's say you're plugging the device into a USB 2.0 port as found on the 2010-2011 MacBook Air models that the drive would be removed from and the theoretical maximum speed is then reduced to 60MB/s. The data itself can also be a determining factor on real world speeds. One large file transfers faster than a bunch of smaller files. It is kinda like driving - you can have a car that has a top speed of 200 mph, but if you're only driving a few feet at a time you're not reaching that full speed with each individual transfer.
Reviewer: apg028 Location: Hong kong Age: 25-34 Experience Level: Home User Owned Product: over 6 months
Rating: 5/5 I need it. Product is good April 19, 2012 I would recommend this item to a friend! This review is from OWC Mercury On-The-Go USB 3.0 External Enclosure for Apple MacBook Air 2010 & 2011 Flash Storage.
OWC 250GB OWC On-The-Go® Pro Mfr P/N: MSU3SSD240GB OWC SKU: OWCMSU3SSD240GB USB 3.0 & 2.0 SSD Storage Solution 3 Year OWC Limited Warranty Ships: Same Day Only $89.99OWC Price $79.00
Add to CartOther World Computing MSU3SSD240GB In Stock, Click to Buy Now
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