6.35mm standard, for electric Screwdriver, manual Screwdriver, electric drill, group general tool, air and other any standard bit 11piece 200mm / 7.9 ” Length Screwdriver set in the following size: tamper proof Bit adopts special antirust for long The Screwdriver drill bit tip, which is for adsorbing screws and improvings work efficiency The head is precisions forgeds Each edges be accurately screw, keepings the screws from slipping and making the operations more, Manufacturer: Yhplxyuus