Single open end wrench

Open-end wrenches are a double-ended wrench with a U-shaped head at each end. They are used for nuts and bolts that are hard to reach. The design allows the user to approach the fastener from two different directions. The flat jaws of these wrenches are slid around nuts or bolt heads and levered for loosening or tightening. The open ends allow the tool to be slid over the nut in tight quarters where there would be insufficient space for a box wrench or a socket, or where the length of a shaft or pipe interferes.