The BlueSpot 7 Pce Wobble Extension Bar Set (1/4", 3/8", 1/2") is manufactured from chrome vanadium steel for increased durability. The spring – ball socket retainer is secure and suitable for ¼”, 3/8” and ½” ratchets. Deep knurling for increased grip. Cut away tip allows for increased precision in hard to reach areas. Set includes: ¼” (2”/4”/6”), 3/8” (3”/6”), ½” (5”/10”)