9 pieces of Impact Hex Socket Bit Set Kits: H4 5 6 8 10 12 14 17 19mm The socket bits tamper proof with center hole. All are 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 electric tools. US-BASED CUSTOMER SERVICE: Available by chat, email, phone, or visit us at our customer service center in La Crosse, WI.