Mount 2.5" SATA hard drives and SSDs in the 3.5" bay of your 2009-2012 Apple Mac Pro using the 2.5" Drive Sled for 2009-2012 Apple Mac Pro from OWC / Other World Computing. This drive sled is designed with powder-coated aluminum that helps to dissipate heat. Additionally, its blue color allows you to identify which bay(s) contain 2.5" drives.
To mount a drive to this sled, simply use the four included hard drive mounting screws to secure to the drive to the sled, and then insert it into an available 3.5" drive bay. This 2.5" Drive Sled aligns the SATA connection from your 2.5" drive to the back plane SATA ports on your Mac Pro. Please note that while this drive sled is compatible with 2009-2012 Mac Pro systems (MacPro4,1 and MacPro5,1), it is not compatible with Mac Pro systems released in 2006 (MacPro1,1), 2007 (MacPro2,1), or 2008 (MacPro3,1).