Four of our 16mm motors. Choose between stock motors (not recommended for combat) or two versions of our custom-made battle-hardened motors. One battle-hardened version has the standard "D" shaft for hubs that use set screws (e.g., Fingertech hubs). The other battle-hardened version has a round shaft for use with the BotKits Candy Wasp hubs. NOTE: BATTLE HARDENED MOTORS DO NOT HAVE THE ABILITY TO BE FACE MOUNTED. Each motor weighs 27.60 grams. The motors are rated for 12 volts of power, and have a no-load speed of 1200 RPM.