781 A 1/4" Connection parts, 781 A/B x 3/8 x 25.2mm x 1/4" - Wera 05042674001, Wera 05042674001 781 C 1/2" Connection parts, 781 C/B x 3/8 x 35.5mm x 1/2"Connection part 1/2" square head socket to 3/8" external square head. For manual and machine-operated tools (non-impact), with ball stop groove to safely lock the socket, knurling at the rear end for manageability during manual use; chrome-vanadium, dull chromed. Wera 05042674001 781 C 1/2" Connection parts, 781 C/B x 3/8 x 35.5mm x 1/2"