As technology advances, computer systems are becoming more compact, allowing the system to be easily transported and/or requiring less physical space. As a result, people are maximizing their system's physical space utility to retain the same functions in a compact space with the use of improved hardware components. Made for Space Saving The FLEX-FIT Duo MB343SPO is a lightweight yet durable 3.5-inch to 5.25-inch mounting kit bracket that utilizes a single standard external 5.25 computer bay to accommodate a 9.5mm Ultra-Slim ODD (optical disk drive) and a 3.5" HDD / device. This would ultimately maximize your system space, allowing the user to fit more devices into a smaller space. Advanced Drive Guiding System Thanks for our advanced drive guiding system; the device installation process is very easy with the FLEX-FIT Duo MB343SPO. ..."Number of Total Expansion Bays: 2Number of 5.25 Bays: 1Number of 3.5" Bays: 1Wireless LAN: NoDrive Interface: Serial ATAColor: BlackMaterial: PlasticForm Factor: InternalCompatible Drive Bay Width: 5.25"Height: 1.6"Width: 5.7"Depth: 5.9"Weight (Approximate): 3.44 ozPackage Contents: 5.25" Ext. Bay to 3.5" HDD/Device Bay+Ultra Slim ODD Bay Mounting Kit Bracket 6 pin Slimline to 15 pin SATA Power Cable User Manual Screws Limited Warranty: 3 YearPackage Contents 5.25" Ext. Bay to 3.5" HDD/Device Bay+Ultra Slim ODD Bay Mounting Kit Bracket 6 pin Slimline to 15 pin SATA Power Cable User Manual Screws "