This is a refurbished optical drive for the PHAT models of the Xbox 360. You can use this to replace a faulty drive in your console, or if you flash it with custom firmware (CFW) 0800v3 you can use this drive to rip iso's of all your original games to preserve them. This firmware allows the drive to talk to your PC normally and when used with Xbox Backup Creator, will let you dump all your originals :).
This is a BenQ Model VAD6038
IMPORTANT DISCLAIMER: All disc drives for the Xbox 360 are "married" to the Xbox console they came from using a unique private key. If you just plop this into your Xbox it won't work. It must be reprogrammed using Jungleflasher with YOUR KEY obtained from your original drive. To use this with the 0800v3 firmware, a key is not required as it will function like a normal drive on your PC. In either case you will need to use the Jungleflasher software and some additional hardware to reprogram this.