This set allows you to mix and match drive sizes for your sockets, ratchet handles, extension bars and other accessories. 1/2" to 3/8" - (12.5mm square hole to 9.5mm square head) Length: 36mm 3/8" to 1/4" - (9.5mm square hole to 6.3mm square head) Length: 26mm 3/8" to 1/2" - (9.5mm square hole to 12.5mm square head) Length: 35mm 1/4" to 3/8" - (6.3mm square hole to 9.5mm square head) Length: 25mm Specification: This set allows you to mix and match drive sizes for your sockets, ratchet handles, extension bars and other accessories. Made of high quality chrome vanadium, CRV alloy, high quality, durable Full tempered heat treatment, high hardness, chrome surface Ideal tool for mechanics, engineers, carpenters or DIYers Sprung Ball Bearing < p> Specification: Hardness: 60HRC Height: about 25mm, 26mm, 35mm, 36mm Main material: Chrome vanadium steel Surface treatment: black electrophoresis Size: 1/2" to 3/8" - (hole 12.5mm square to 9.5mm square head) Length: 36mm 3/8" to 1/4" - (9.5mm square hole to 6.3mm square head) Length: 26mm 3/8" to 1/2" - (9.5mm square hole to 12.5mm square head) Length: 35mm 1/4" to 3/8" - (hole 6.3mm square to 9.5mm square head) Length: 25mm Contneu: 4pcs Increaser and Reducer Adapters