2 players are running forward and backward while facing the same direction.
When the first player has taken 2-3 steps forward, the second player has taken 2-3 steps backward.
The first player passes the ball to the second by leading her arm across her chest and flipping the ball backward with her fingertips.
Then the first player runs backward.
The second player receives the ball while moving forward and after 2-3 steps the same pass is made by the second player to the first and so on.
After a while both players turn around facing the opposite direction and the drill is repeated to train both arms.