12mm. According to the inquiry of Bosch go2, the weight is 36g, the maximum drilling diameter of batch head is 12mm, and the warranty period of the whole machine is one year. Bosch GO2 is designed to replace the handle screwdriver, and its main function is to screw the screw. Because of the voltage, torque and speed, it can be used as a punching tool to punch holes in wood plastics and other materials.