ITEM NAME:DC Motor 555 550 545 540 5 Series Motor Base Mounting Bracket Holder Seat 3C DC Motor 555 550 545 540 5 Series Motor Base Mounting Bracket Holder Seat 3C a.imagelink a:hover.imagelink {color:#000006;.[Size]: bottom 40 43mm, height 47mm. [Bottom fixed pitch]: 25mm, 30mm (horizontal). [Bottom fixed aperture]: M3 hole. [Fixed hole pitch]: 25mm. [Center aperture]: about 12.8mm. [Thickness]: 3mm thick aluminum alloy.