Package Contents:5 PCS M0.6 1/8-inch hole ( 12T, 13T, 14T, 15T,16T) with 5 Grub Screws Each gear is designed with a 0.6 Metric Pitch,The gears have a 1/8-inch hole size, which is compatible with 3.175mm shafts, a common size for 1/10 RC car motors. 5 PCS Metal Gear Set are hardened to increase their durability and resistance to wear, which is essential for high-performance applications where the gears are under constant stress. Each gear comes with a grub screw (also known as a set screw) for secure attachment to the motor shaft.