They are engineered specifically for use with impact tools, using the most up to date industrial specifications. Grey Pneumatic Impact Sockets are made from high quality alloy steel (chrome-molybdenum). Thorough and exact heat treatment insures the correct balance of strength and durability. Grey Pneumatic Impact Sockets are tested to the highest specifications to deliver outstanding performance. Increased Strength-Transfers the pressure from the thinnest part of the socket wall toward the thicker section, resulting in increased strength. Increased Torque-Allows up to 20% more torque to be applied than on standard hex impact sockets.