Mini 4WD Super Gear for Double Shaft Motors, Pink Gear, Lightweight, Chamfered, and Pressure Treated. The hole size is 2mm, making this a precision-tuned gear. Processed using a dedicated aluminum plate and a drill press for gear processing. A new gear was opened, processed, and then sealed in a bag. Lightweight gears improve responsiveness and acceleration. For those seeking speed beyond others, please consider this.