Connection parts, 5-piece set For manual and machine-operated tools (non-impact), with ball stop groove, knurling at the rear end for manageability during manual use; chrome-vanadium, brushed chrome-plated finish 781 A: 1/4" socket square head drive, for 3/8" and 1/2" square head socket wrench inserts with ball lock; 781 B: 3/8" socket square head drive, for 1/4" and 1/2" square head socket wrench inserts with ball lock; 781 C: 1/2" socket square head drive, for 3/8" square head socket wrench inserts with ball lock.
