Made of CR-V steel with mirror-polished, for strength, durability, rust and corrosion resistance.3 pieces universal joints: 1/4″Dr., 3/8″Dr., 1/2″Dr. 4 pieces adapters:1/4″F x 3/8″M, 1/4″M x 3/8″F,1/2″F x 3/8″M, 1/2″M x 3/8″F.Fluent groove design, attaches tools easily. Apply to 1/4″, 3/8″, and 1/2″ Drives tools.Spring-loaded detent balls design, makes it latch onto the tool securely and firmly. √ Gain access to fasteners hard to reach and changing angle of force, save both time and labour. √ Vastool U-Joint could be used under various situations, such as car, bike, all kinds of mechanical maintenance.Gain access to fasteners hard to reach and changing angle of force, save both time and labor.