• Bushings mounted with a "lock pin" plunger: allows the sleeve of the element (extension, ratchet) to be secured. Protection radius of the square: distributes the load and prevents the bushing from breaking. Sockets 100% forged turned. Made of chrome-vanadium steel, the best material for the manufacture of sockets. Hardness: from 40 to 46 Hrc. Optimum hardness / longevity ratio.