Offspinners Harbhajan Singh, Graeme Swann and Mohammad Hafeez have excelled in bowling arm balls.
In this case, the stock ball will turn away from the right-handed batsman and the arm-ball would swing in, allowing the bowler to beat the inside edge of the bat and attack the stumps.
Daniel Vettori, Rangana Herath and Derek Underwood are other examples of left-arm orthodox bowlers renowned for use of an inswinging arm ball to good effect.
Vettori famously bowled Darren Maddy with a perfect arm ball at the Oval Test Match of 1999.
[1] Some recent examples of left-arm orthodox spinners who have excelled in bowling arm balls are Ravindra Jadeja, Axar Patel, Akeal Hosein, Shakib Al Hasan and Sophie Ecclestone.