1/2" Sq.Dr. Shallow air Impact Sockets, 6PT/MM: 1) Both with groove and without groove ... -41MM 3) ISO9001 1/2" Sq.Dr. Shallow air Impact Sockets, 6PT / MM Specifications:8, 9, 10, 11, 12, 13, ... , 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 32, 33, 34, 35, 36, 38 ... the best combination of strength and impact resistance.Optimum wall thickness design for strength and access on fasteners having ...