Direct Torque Technology, Polished chrome vanadium finish, Knurled control ring, Hard stamped markings, Full Lifetime Warranty. Direct Torque Technology helps prevent rounding of fasteners. Knurled Control Ring for added grip when handling the socket. Chamfered open end for easier engagement of fasteners. Hard Stamped markings to prevent loss of identification over time. Full Polish Chrome Vanadium finish helps prevent chipping and flaking under toughest environments.