How the arms move is specific to the slap type.
Soft: Contact is the top of the ball. Triangle flip and stop at contact
Bounce: Contact is top of the ball and cut down through the middle of the ball. Knob down through the ball and snap to extension toward the ground. Hands stay below the barrel until snap. Hands never crossover each other.
Hard: Contact is middle to lower half of the ball and extend out and away. Triangle flip to confident single lady.