GoolRC 2Pcs 48DP 3.175mm 14T Motor Pinion Gear for RC Car Brushed Brushless Motor Suitable shaft diameter: 3.175mm Hard anodized on the gear surface Rust-proof treatment on the surface of gears The gears are milled by precisely Tanwai milling machine A M3 set screw(12.9 level)has been added to each pinion gear