For installing or servicing heating, air conditioning or refrigeration units. 5/16 in and 3/16 in Hex Key Wrench Inserts (optional) 1/4 in 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 in long.