The CP058 is a 3 x 3.5" hard drive cage in 2x 5.25" drive bay(variation of MB153SP-B) with a tool-less drive installation design built into the trays. We understand that sometimes managing 3.5” hard drives can be a hassle, especially when you have to screw in drives onto trays. With these trays, just place the drive in the tray and insert into the cage in the computer and you can access the drive without the need to screw 4x screws in order to secure the drives. CP053 is what you need to make your daily drive hot swapping routine a breeze! Furthermore, for applications where require extra drive stability and security, an optional bottom tray screw holes are provided for added drive protection.