Precision Bits Set screwdriver Repair Mobile Phone Camera Computer Holder Hex Shank 4mm ADAPTER:If your screwdriver takes 1/4"(6.35mm) bits and you want to use 4mm bits. This adapter is for you.6.35mm ADAPTER:If your screwdriver takes 4mm bits and you want to use 6.35mm bits. This adapter is for you. Material : Chrome-vanadium Steel Model Number : ADA-001.ADA-002 Small size, easy to carry and store, Manufacturer: Waningmoto