It is measured from the center of a 2.135-metre (7-foot) circle into a 40-degree sector. The circle contains a 10 cm (4 inch) high stop board in front of it; if the competitor walks on or out of the circle, the throw is disqualified. The shot put consists of a metal cylinder about 1.5 metres long with a hemispherical end cap at one end and a rubber stopper at the other. When thrown, the stopper first makes contact with the ground inside the circle, followed by the cap. The shot put can be thrown either forward or backward. To forward throw, the athlete starts by bending their knees and swinging their arms back behind their body. Then they stand up straight and thrust their hips forward, allowing the arms to swing forward and release the shot put. Throwing forward gets its name because the aim is to have the shot go as far as possible. Backward throwing works similarly except that the legs and arms are swung backwards after starting position instead of forward. Backward throws are useful for clearing out lanes in front of the pit or for filling it up if there is not enough material available forward. Forward throws are used to get the most distance possible with a given shot. It is important to note that while distance is important, so is how high you can throw it. The higher you can throw it, the more points you will score.