A lug wrench is a tool used to loosen or tighten the lug nuts on a vehicle's wheels. It typically has a long handle for leverage and may come in a cross shape or a simple L shape. The design allows users to apply sufficient force to remove or secure the nuts, which hold the wheel in place. Lug wrenches are often included in a vehicle's emergency kit, alongside a jack for changing tires. They are essential for roadside assistance, enabling drivers to replace flat tires quickly and safely. Proper use of a lug wrench can prevent damage to the lug nuts and ensure a secure fit.