The MB663USR-1S is built for both internal and external usage. The 3.5" internal aluminum receiving dock has a SATA connection to allow maximum SATA transfer rate of up to 300 MB/ sec and it fits into most 3.5" bay on the computer. The SATA type II connector provides a safer and reliable connection than the previous SATA since it clasps to the SATA port. For external use, the portable enclosure comes with a USB 2.0 which allows user to carry their data to any laptop or desktop. Installing a 2.5" SATA hard drive requires no tools or screws because the ejection button releases a mechanical arm that allows you to have an access into the portable enclosure to insert the hard drive in seconds. The spring inside the portable enclosure secures the hard drive and absorbs the vibration that occurs within the hard drive motor. The aluminum body also dissipates heat to allow the hard drive to maintain a cool environment. The MB663USR series is a perfect solution for DVR (Digital Video Recording) and surveillance systems since it allows professionals to transfer data conveniently by USB Bus-powered.