A metal-frame pool is a type of above-ground pool whose foundation consists of a support structure made of steel or other metal pipes. This structure gives the pool its shape and ensures its stability. An inner pool liner, made of durable and impermeable material—most commonly several layers of PVC—is inserted into the finished frame. The liner serves to hold the water. These pools are supplied as kits designed for DIY assembly on a solid, level surface. Compared to self-supporting or inflatable pools, they offer greater strength and a longer service life. They are manufactured in various shapes, such as circular or rectangular, and sizes.