Later in his childhood he perfected the delivery with a real cricket ball. The nature of the cricket ball slightly varies with its manufacturer. Spin bowlers are generally given the task of bowling with an old, worn cricket ball. Examples include a tennis ball and a plastic version of the cricket ball. Direct injuries are due to impact with the cricket ball, bat or ground. Originally the British used a white painted leather covered cricket ball. Younis' trademark was his ability to reverse swing a cricket ball at high speed. The circular design was meant to denote the cricket ball. His luxury choices were a piano and a cricket ball. A simple example might be accidentally hitting someone with a cricket ball. A tennis ball is often used rather than the harder cricket ball. When the cricket ball is inside the boundary, it is live. Knocking-in involves striking the surface with an old cricket ball or a special mallet. When the door opens, a cricket ball rolls out. Alternatively a black screen is used to contrast the white Limited Overs cricket ball.