TUSK's range of IMPACT SOCKETS are manufactured from premium grade Chrome Molybdenum (Chrome Alloy), perfect for either Tradesmen or DIY - Chrome sockets flex. Impact sockets do not. This is partially material and partially thickness. Chrome sockets are made of a harder but, more brittle material. The increased ductility (give or flex factor) of a "Chrome Moly" socket makes it better for impact use and makes these sockets less likely to shatter from the high torque and vibration of an impact wrench.