Wrench tattoo means strength and courage. Wrench is a commonly used installation and disassembly tool. It is a manual tool that uses the lever principle to turn bolts, screws, nuts and other threads to hold the opening or socket fastener of bolts or nuts. Wrenches are usually made of structural steel made of carbon or alloy materials.

The wrench is usually provided with an opening or sleeve hole for clamping the bolt or nut at one or both ends of the handle. When in use, the bolt or nut can be screwed by applying an external force on the handle along the thread rotation direction.

Source: @bingtat2