Greenlee Open Ended & Box Wrenches
Open ended wrenches feature a head with a U-shaped opening. This opening applies torque to two sides of the a nut or bolt when the wrench is turned. Box wrenches feature closed ring or cap. This ring fits over the nut or bolt, and applies torque to all sides as the wrench is turned. Combination wrenches feature two heads: an open-ended wrench on one side, and a box-head wrench on the other.