Chrome plated carbon steel with spring ball detent. Set includes sizes 1/2″(F) x 3/8″(M), 3/8″(F) x 1/4″(M), 3/8″(F) x 1/2″(M), 1/4″(F) x 3/8″(M). Ideal for use as a converter for ¼”, 3/8” & ½” ratchets & flexi bars. NOT SUITABLE FOR IMPACT DRIVERS OR WRENCHES – Amtech V6520/ V6525 OR EQUIVALENT MANUFACTURERS MODELS .