Heavy bags are large weighted bags shaped in a long cylindrical form. Most bags are suspended from the ceiling or a stand via chains, but there are some free-standing bags that are attached to heavy bases. They usually weigh somewhere between 50 lbs and 250 lbs. They are used to practice combination punching with power. Heavier bags will remain more still, while lighters bags will move more as they are punches. Because of this, lighter bags can be useful for training complex combinations that involve both offense and defense; however, lighter bags are less durable than others and can break faster. The bag is usually made of leather or synthetic casing filled with rags, sand, grain, or even rice. Since the lighter bags require thinner leather or canvas to hold the filling, they are more often subject to wear and tear.