About This Item: Machined clear acrylic housing, 6061 Aluminum Machined adjustable skid and 56T Hard Steel spur gear. Heavy duty machined steel gear set . Steel ball bearings and shaft. Complete Assembled. Fits RC Crawler, Rigs,Comp builds diy. Specifications: Transmission Size: Length 84mm, Width: 48mm, Height: 53mm Delrin Skid Size: Width: 78mm, Skid Mount Width: 38mm (hole to hole) 56T Spur Gear and 9T Pinion Gear Fits 3.175mm shaft diameter motors Heavy duty Weight :197g / set, improves balance and handling. Package List: 1x Transmission Set