Forged from the finest chrome molybdenum alloy steel - the best choice for strength and durability. Radius corner design - to extend the life of fasteners. Steel ball retainer on male end. Included in a heavy molded storage tray. Fully guaranteed No doubt, Sunex tools offer one of the most complete and toughest Impact Socket lines around. This 1/2" drive extensions are designed to tackle the toughest jobs with solid durability and keeps them pounding job after job. Also each socket extension features a radius corner design, causing the socket to grab the sturdy wall of the fastener instead of grabbing the corners, resulting in less wear on the fastener. The following sizes included: 3", 5", 10" and 15".