The ER wrench is a common mounting and removal tool.
Use the principle of leverage to twist bolts, screws, nuts, and other hand tools that hold the opening or socket firmware of the bolt or nut. The wrench usually has an external force applied to the one end or both ends of the handle to apply an external force to the external force of the handle, so that the bolt or nut can be screwed to the opening or sleeve hole of the bolt or nut.