The BlueSpot Impact Socket Adaptor is manufactured from chrome vanadium steel for increased durability. They feature a ball bearing socket and are ideal for high impact use. The set contains a selection of the most popular sizes: 2 x 1/4in Drive (M) x 3/8in Drive (F) 1 x 3/8in Drive (M) x 1/2in Drive (F) 1 x 3/4in Drive (M) x 1/2in Drive (F) 2 x 3/8in Drive (M) x 1/4in Drive (F) 2 x 1/2in Drive (M) x 3/8in Drive (F)