Specifications: Material: Metal Teeth: 64T and 17T 21T 26T 29T Height: 11mm (motor gear); 9mm (main gear) Tip diameter: 17T: 11.5mm 21T: 14mm 26T: 16.5mm 29T: 18.5mm 64T: 40mm Suitable shaft diameter: 3.175mm (motor gear); 5mm (main gear) Package information: Package size: 9 * 6 * 2cm / 3.5 * 2.0 * 0.6in Package weight: 70g / 2.17oz Polybag package Package list: 1 * 17T Gear 1 * 21T Gear 1 * 26T Gear 1 * 29T Gear 1 * 64T Gear