This scale is specifically designed to be used in bowling proshops.
There is a holder on one end for the ball, a pivot point, and weights on the other. You use the weights to measure the weight of half of the ball at a time.
By doing this you can find the center of gravity on a ball and determine the static weights (Top weight, side weight, finger weight, etc).
You cannot properly drill a ball without one. Any good proshop will use one.