from the finest chromium-plate molybdenum alloy steel -- the best choice for strength and durabilityRadius corner design - to extend the life of fastenersThe design drives the stemma of the fastener instead of the cornerProvides increased strength, but also avoids rounding of rusted or mangled fastenersFully guaranteedNo doubt, Sunex tools offer one of the most consummate and toughest Impact Socket lines around. This 1 ; drive socket adapter a ball retainer and is designed to tackle the toughest jobs with sound durability and keeps them pounding job after job. It also a region corner design, causing the socket to grab the stout wall of the fastener instead of grabbing the corners, resulting in less wear on the fastener.