Bullet Point: This is DC motor kit. There are 112pcs/set, which are often needed by toys. Others include single-layer gears, double-layer gears, crown gears, main shaft gears, worm gears, pulleys, fixed brackets, plastic plates, belts, bushings, wheels, axles, Switches, battery boxes, propellers, stickers, angle irons, etc. The motor shaft diameter is 2mm, so all gears of the matched package are 2mm. To provide parts support for assembling small cars and model toys. If you need to complete a complete model, you need to consider yourself. It is practical and useful. Package included: Spindle layer gear*8Pcs Single gear *10Pcs Crown gear*2Pcs Double layer gear *8Pcs Pulley*9Pcs Worm, shaft sleeve*18Pcs Motor, bracket*8Pcs Wheel axle *24Pcs Propeller*3Pcs Rubber band*15Pcs Other: Angle iron (4 pcs), viscose (2 pcs), green board*1