Impact Hex Socket Bit H4 mm The socket bit is 3-1/8" (80mm) long. 1/2" (12.7mm) Sqaure Drive with drive release holes. Drop forged black chrome moly steel (CR-MO). | Industrial grade quality. Suitable for air tools and power tools. US-BASED CUSTOMER SERVICE: Available by chat, email, phone, or visit us at our customer service center in La Crosse, WI.