Ineffective - Cups hard, stiff, no flex and won't stay on polisher.
I discovered the cups for the polisher were stiff, like a hard rubber, little or no flex. When attempting to get in and around the curves of the of the teeth, the cup would fly off. Even with moderate pressure on the flat surfaces of the teeth, it would do the same.  The cups should be made with a flexible type product and screw in on the stubby shaft of the device. The polisher also doesn't do well for getting to the side and back teeth. Returning as defective product - doesn't work as described.
Rating: 1 stars