Smart features that save your knuckles and your time. hilmor's Straight Service Wrench makes changing sizes quick and easy, With its reversible feature which makes maneuvering around cramped spaces a thing of the past. The reversible Ratchet Wrench has square openings of 1/4 and 3/16 Inch on one end and 3/8 and 5/16 Inch on the other end. And, when it comes to accessing liquid- and suction-based valves, and mini ductless split condensers, just reach for hilmor's Hex Key Adapter included in this kit. It works on 3/16 and 5/16 Inch hex valves.