Review (2/5): Design flaw
This works well, but has a major design flaw: The on/off button and the button that varies the water pressure are right next to each other. When you are using the flosser in the shower (with your eyes shut so you don't get hit in the eye) you often miss the on/off button and increase the water pressure by mistake. And let me tell you, the highest water pressure is hazardous. In one case it cut my lip!
They should have the two buttons separated, or at least distinguished so that you don't mistakenly rivet yourself with high water pressure.