A pool noodle is a cylindrical piece of buoyant polyethylene foam, sometimes hollow. Noodles are used by people of all ages while swimming. Pool noodles are useful when learning to swim, for floating, for rescue reaching, in various forms of water play, and for aquatic exercise. The most common dimensions are about 160 centimetres (63 in) in length and 7 centimetres (2.8 in) in diameter. The pool noodle is also used for people who experience difficulties in swimming. The pool noodle is often used to protect sharp edges and corners.