The size for floppy drives, CD-ROM drives, or 2.5" SSD drives. We're upgrading a bunch of our public computers to SSDs for a faster boot time. The drive carrier/caddy in Optiplex 9010s don't come with screws for the 2.5" bracket which happens to be on the bottom side of the caddy. I checked MSU Surplus already. They're out this week. [Machine Screw: M3, 5mm Length, Phillips (25-pack)] Thanks. Don Bosman Information Technologist MSU Libraries 366 W. Circle Drive - Rm.W441 East Lansing, MI 48824-1048 517-884-0873