10PCS 12 POINT TRIPLE SQUARE SPLINED DRIVE BIT SOCK SET M4-M18 1/4" 3/8" 1/2" Manufactured from chrome-vanadium steel with heat treated for extra strength and durability. Each bit has its size imprinted on the bit itself, making it easy to identify them after you've removed a handful from the case. Material: Chrome Vanadium Steel Package Weight: approx.0.65kg Socket Size: 1/4" Drive(37mmL): M4, M5, M6 3/8" Drive(48mmL): M8, M9, M10, M12 3/8" Drive Tamper Proof(48mmL): M14 1/2" Drive Tamper Proof(55mmL): M16, M18