flexiDOCK MB521SP-B
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mb741sp-b mb991ik-b mb991sk-b mb491skl-b

flexiDOCK brings the quality and ease-of-use of a professional solution to the consumer market. With support for 2.5" hard drives or SSDs ranging from 5mm – 15mm height, the MB521SP-B fits almost any type of the 2.5” drives include 15mm height 5TB+ high capacity laptop drives and requires only a single external 3.5" drive bay. Our new tray-less design has no doors, allowing for drives to be switched out within seconds. This is an improvement to many traditional hard drive docking stations that leave the drive sticking out and looking cluttered. The easy to press ejection button offers rapid drive ejection in a smooth, quick action. The drive power switch allows drive to be turned on and off in an instant. The metal body with an air ventilating design keeps your drives at optimal temperature.


The flexiDOCK MB521SP-B is the perfect solution for anyone who needs quick access to data from high capacity laptop drives or high speed SSDs; Media professionals editing and moving large files, data recovery specialists constantly swapping drives, and IT technicians maintaining regular backups of critical data.

The World’s First Professional Docking Made for 3.5” Bay

flexiDOCK brings the convenience of a HDD docking station, with the performance of a HDD mobile rack. The MB521SP-B turns your external 3.5” bay into a hot-swappable SSD / HDD dock to easily access all kind of 2.5” drives within the dock. flexiDOCK installs into your system in minutes with only a few screws, and is ready to operate. Once installed, the flexiDOCK MB521SP-B supports 1 x 2.5” SAS/SATA HDD/SSD drives ranging from 5mm to 15mm in height. It also supports SATA 6Gbps transfer speeds and hot-swap functionality, using your drives to their full extent has never been easier.

Different by Design

When working with multiple drives, constantly swapping between drive caddies / trays can slow your workflow to a crawl. That’s why we’ve taken trays and doors completely out of the equation with our new flexiDOCK MB521SP-B. Our new system allows drives to be inserted in seconds and sit flush with the computer's front panel, reducing clutter and protecting your drives from environmental hazards. When a drive is inserted into flexiDOCK, an eject button is revealed along with a LED drive activity light. To eject your drive, simply press the eject button back in and your drive will pop out. You can also turn off drive’s power anytime by switching the front accessible power slide switch.


Profession Specific


With the new door-less design that allows users to quickly and easily change out SSDs or drives. Video professionals and hobbyists use this feature to quickly edit their videos, when large projects call for multiple drives. Forensic customers benefit from the ability to easily access client’s SSD or HDD within the forensic workstation. IT professionals and computer repair technicians utilize this feature to effortlessly read / write data from multiple drives. The flexiDOCK MB521SP-B is an affordable yet powerful tool that helps professionals do their jobs more time efficiently and effectively.


Built for Enterprise

We’ve designed flexiDOCK to handle professional applications, while maintaining a consumer-friendly price point. The MB521SP-B is capable of holding up in the harshest environments, with the heavy duty metal casing throughout the entire device, it can be used in various enterprise systems including: image processing workstation, digital forensic workstation, as well as manufacturing conditions such as embedded control systems and factory automation systems. The full metal design also allows heat dissipation transfer from the hard drives or SSDs throughout the mobile rack. In addition, Multi-Flow Technology routes air flow effectively for excellent passive cooling through meticulously designed front, rear, top and bottom ventilation slots.


Safety Enhanced Drive Guiding Mechanism


Since 2.5” SSDs and hard drives come with different drive heights and dimension may vary from manufacturer to manufacturer, in order to protect your drives, we have designed a safety enhanced drive guiding mechanism that prevents accidental drive ejection. There are two drive guiding pecks on either side of the drive and a metal flap in the rear that adjusts automatically based on drive's height. Each guiding pecks clamp the drive tightly while the adjustable metal flap pushes the drive down, making a stable SATA connection. Ultimately, these features are designed to prevent unintended drive ejection that may result in possible data damage.


Optional EZConvert MB703M2P-B for M.2 SATA SSD


If you are looking to use a M.2 SATA SSD with the flexiDOCK MB521SP-B, pair it with our EZConvert MB703M2P-B M.2 SSD to 2.5” form factor adapter featuring tool-less adjustable locker to secure your M.2 in place. To learn more about EZConvert MB703M2P-B please click HERE.


Optional Flex-Fit MB343SP for External 5.25” Bay

When using FlexiDOCK in an external 5.25" drive bay, Flex-Fit MB343SP can be used as an adapter for converting an external 5.25" drive bay into an external 3.5" drive bay. To learn more about Flex-Fit MB343SP please click HERE.

Suggested Applications
Data backup, data cloning, audio & video editing, digital forensic, drive recovery or any applications where drive hot-swap is required.
Key Features

* Supports docking 1 x 2.5” SAS/SATA HDD/SSD with SATA hot-swap functionality (5mm – 15mm)
* Supports SATA 3.0 6Gbps or SAS 3.0 12Gbps (single channel)
* Fits any external 3.5” bay
* Full metal chassis with industrial ABS plastic for full protection to the drive
* Completely tray-less design and accepts bare drives without trays or holders
* Drive door-less design for quick hot-swapping
* Safety enhanced drive ejection button to prevent accidental drive ejection
* Large individual drive eject button with cool blue drive activity LED
* Flush drive insertion design fully protects drives from possible environmental damage
* Front accessible drive power switch
* Multi-Flow Technology - provides excellent passive cooling
* Backed with 3-year manufacturer warranty
* Ideal 2.5” SSD / HDD docking for system that requires easy hot-swap as mobile computers, data center rackmount computers and rackmount server systems, industrial automation control system, military computers and OEM / ODM systems


3 Years Warranty
ICY DOCK flexiDOCK MB521SP-B 2.5 inch Hot-Swap SATA / SAS HDD / SSD Dock Trayless Mobile Rack Backplane Cage for External 3.5" Drive Bay
Product Name :
2.5” SSD Dock Trayless Mobile Rack for Extertal 3.5” Drive Bay
Model Number :
Color :
Support Drive Size :
2.5" SSD / HDD
Compatible Drive Type :
SATA / Single channel SAS (SAS host required)
Number of Drives :
Max Drive Height :
Drive Bay :
1 x external 3.5" drive bay
Host Interface :
1 x SATA 7pin
Power Input :
1 x SATA 15pin
Transfer Rate :
SATA 3.0 up to 6Gbps / SAS 3.0 up to 12Gbps (single channel)
Support HDD Capacity :
No Limitation
Drive Cooling :
Metal heat dispersion with passive cooling
Structure / Material :
Metal with parital plastic
Support Hot-Swap :
Product Dimension (L x W x H) :
128.5 x 101.6 x 25.4mm
Product Net Weight :
Package Gross Weight :
Drive Activity LED Indication :
Drive power: solid blue; HDD access: flashing blue
Package contents :
1 - Device, 1 - user manual, 4 - screw
Product Name :
2.5” SSD Dock Trayless Hot-Swap SATA Mobile Rack for Ext 3.5” Bay
SATA Connector Insertion Rate :
Humidity :
5%~65% RH
Operating Temperature :
0°C to 60°C (32°F to 140°F)
Storage Temperature :
-35°C to 70°C (-31°F to 158°F)
Compliance :
Warranty :
3 years
Frequent Asked Questions
Q: Does MB521SP-B support the new SATA 3.3 Power Disable feature (PWDIS)?

A: The MB521SP-B does not support the SATA 3.3 PWDIS feature. If you install the SATA HDD/SSD with PWDIS in MB521SP-B, the drive will not spin, and the system won't detect the drive. See the list below for known SATA HDD/SSD with the PWDIS feature.


Known SATA HDD/SSD with Power Disable Feature (PWDIS)

WD Ultrastar C15K600
HUC156030CS4200/1/4/5 HUC156045CS4200/1/4/5 HUC156060CS4200/1/4/5
HUC156030CSS200/1/4/5 HUC156045CSS200/1/4/5 HUC156060CSS200/1/4/5
Samsung PM883
Seagate EXOS 15E900
ST300MP0006 ST300MP0016 ST300MP0026
ST300MP0096 ST300MP0106 ST300MP0116
ST600MP0006 ST600MP0016 ST600MP0026
ST600MP0036 ST600MP0126 ST600MP0136
ST600MP0146 ST600MP0156 ST900MP0006
ST900MP0016 ST900MP0026 ST900MP0126
ST900MP0136 ST900MP0146 ST900MP0156


Note: the SAS hard drive or SSD does not use the Pin 3 of SATA power connector for PWDIS feature and compatible with MB521SP-B.


While we recommend to avoid using the SATA HDD/SSD with PWDIS, you can use the methods below to disable the PWDIS feature physically if you already purchased the drive:


Method 1 – Using the Molex to SATA adapter or cable to disconnect the power to Pin 3 of the SATA power connector.


Molex to SATA Adapter   Molex to SATA Cable
Molex to SATA Adapter   Molex to SATA Cable


Method 2 – Placing Kapton tape on Pin 1-3 of the SATA power connector to isolate the 3.3V power, as shown below.


Kapton tape SATA power connector


Please contact tech@icydock.com if the problem persists.






Introducing the ICY DOCK flexiDock, the first internal 2.5” SSD / HDD docking station, made specifically for quick and easy drive swapping with individual power switch per cartridge. Designed with intended application in mind, ICY DOCK has brought the next level of convenience towards various applications, such as computer repair shop for multi OS drive swapping, autonomous vehicle for continuous data recording, media professional for hassle free file editing among drives and more! Check out flexiDOCK product selection below and don't miss out the chance to take advantage on the special promotion deal!



  Key Features:

      - Multi-flow technology - provides excellent passive cooling
      - Full metal chassis with industrial ABS plastic for full protection to the drive
      - Completely tool-less design and accepts bare drives without trays or holders
      - Flush drive insertion design fully protects drives from possible environmental damage
      - Backed with 3-year manufacturer warranty



11740 Clark St.
Arcadia, CA 91006
Tel: 626.956.8800
Fax: 626.956.8811



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Product Review

By: OverClockedInside

Posted: Sep 1, 2020


ICY DOCK MB521SP-B flexiDOCK Review


"Today we take a look at Icy Docks Hot Swap removable frame MB741SP-B. This ExpressCage offers a special feature, because unlike most other removable frames available today, it is compatible to external 3.5 inch slots. In the following review on OCinside.de we have tested it extensively and created a small video."


Read more: https://www.ocinside.de/test/icy_dock_mb521sp_b_d/






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