Larger efficient servo fan/heatsink is about 3-5/8" diameter x 2" thick. Has 4 push-in nylon mounting posts. Operates on 12VDC @ 0.17Amp. Made by Foxcom. This fan has a 4 slot connector - just connect (+) to green lead and (-) to black lead to operate. These are new nut come to us in bulk so may have a few cosmetic scratches or marks on case.