An arm ball is a type of delivery in cricket. It is a variation delivery bowled by an off spin bowler or slow left-arm orthodox bowler. It is the finger spin equivalent of a wrist spinner's slider or zooter.
In contrast to the stock delivery, an arm ball is delivered without rolling the fingers down the side of the ball on release. This means the ball has little or no spin on it, and it does not turn appreciably off the pitch. Instead, it travels straight on in the direction of the arm, from which it derives its name. However, by keeping the seam upright, the bowler can also hope to obtain some outswing away from the right-handed batsman, thereby confusing the batsman who expects the ball to turn.
The arm ball is best used as a surprise variation by a spinner who is turning the ball considerably. A complacent or poorly skilled batsman playing for the expected spin can be taken by surprise and get out bowled or lbw, or edge the ball with the outside edge of the bat to offer a catch to the wicket-keeper or slip fielders. Sanath Jayasuriya,Saqlain Mushtaq, Daniel Vettori, Mohammad Rafique and Monty Panesar use the arm ball to good effect. India's Bishen Singh Bedi is arguably the best known exponent of this delivery.