For installing or servicing heating, air conditioning or refrigeration units. 5/16" & 3/16" Hex Key Wrench Inserts (optional) 1/4" square drive shanks fit Malco RRW4 and RRW4 Ratchet Wrenches. Facilitates easy ratcheting action for servicing hard to access valves common in air condition and refrigeration condensing units. 1-5/8" long.