A hammer wrench is designed to work with a hammer, the wrench provides an area in which to strike it with a hammer. The reason for this is provide extra torque to help loosen a bolt, nut or fastener that is stuck.
A striking wrench is usually used when the area where the bolt, nut or fastener is located does not allow a socket to fit onto it. The striking end of a hammer wrench has a flat end which can be struck with a hammer to provide extra torque for loosening bolts, nuts and fasteners that are stuck in tight spaces and is usually made from a hard metal such as forged alloy steel or chrome vanadium which helps prolong the life of the striking wrench. A striking wrench can also be used by checking if it will fit over the head of the bolt, nut or fastener you need to remove and striking it with a hammer until loosened. If this does not work for your particular application there are other styles striking wrenches available that may be better suited for your needs.
There are many different styles of striking wrenches available depending on the size of bolt, nut or fastener they will be used to loosen. These wrenches will fit a 6 point or 12 point bolt or nut and either have a straight handle or an offset handle depending upon the needs of the end user.