The Yellow Jacket 60616 Offset Service Wrench 3/16″, 1/4″, 5/16″, 3/8″ Sq is built with the knuckle saver design for convenience in tight areas. It includes 1/4″ and 3/16″ square openings on one end, and 3/8″ and 5/16″ square openings on the other. These Yellow Jacket 60616 ratcheting box-end wrenches, also known as HVAC wrenches or refrigeration wrenches, have a 4-pt. Box end design allows more contact with the fastener's sides than a 6-pt. Or 12-pt. Style and prevents rounding the fastener's corners. They can be used on square pins and have a 4-in-1 kind that allows the wrench to be flipped over to access four different SAE (inch) size fasteners. The ratcheting box ends have a gear mechanism that allows the wrench to rotate freely in one direction without removing the wrench head from the pin and repositioning the twist. Box-end wrenches can access valves on residential and commercial refrigeration units. The Yellow Jacket 60616 Offset Service Ratchet Wrench comes with some fantastic features. To begin with, it has a knuckle saver design for convenience in tight areas.