Lug nuts may be removed using a lug, socket, or impact wrench. If the wheel is to be removed, an automotive jack to raise the vehicle and some wheel chocks would be used as well. Wheels that have hubcaps or wheel covers need these removed beforehand, typically with a screwdriver, flatbar, or prybar. Lug nuts can be difficult to remove, as they may become frozen to the wheel stud. In such cases a breaker bar or repeated blows from an impact wrench can be used to free them. Alternating between tightening and loosening can free especially stubborn lug nuts.