Kincrome Impact Sockets & Accessories are manufactured from chrome molybdenum steel (Cr-Mo), hardened and tempered to perform in extreme conditions. They are designed to be used with pneumatic and power tools where higher torque and force is required. Kincrome Impact Sockets and Accessories meet and exceed the following international standards - ANSI, DIN 3121 & 3129When using impact tools the following safety precautions should be taken: Always use protective eyewear DO NOT hold the Socket or Accessory while the tool is in operation DO NOT use damaged or worn Sockets or Accessories DO NOT continue to "hammer" a fastener once it becomes tight DO NOT use standard Sockets or Accessories on impact tools | Kincrome Impact Socket Extension Bar Set - 4 Piece