SmileDirectClub Smile Spa Ultrasonic and UV Cleaning Machine

I'm on my third unit and I will buy another when this one breaks down because despite the eventual failures this is still convenient and effective. This has been my experience:1) First unit, 4 months in: The hinge broke and the lid separated. I had to buy a new one. Fix: Right out of the box, lay a narrow strip of duct tape across the hinge to reinforce it.2) Second unit, 2 months in: The UV bulb partially burned out. On activation, the bulb came on to full brightness but then, within a second, dimmed to half brightness. The bulb should come on and stay on at a consistent brightness level. The sonic cleaning process doesn't rely on the UV bulb, so I continued to use this unit despite the bulb failure.3) Second unit, 10 months in: The start button stopped working consistently -- the unit would turn on about once every 5-10 button pushes, and eventually stopped coming on at all. I bought a third unit.4) Third unit, 2 months in: Going strong. Hinge is reinforced, UV bulb is bright.Why I keep buying it: It is very well designed for cleaning my retainers and keeping them safe and out of sight when I am not wearing them. I use plain tap water (no cleaner tabs or mouthwash) and the sonic cleaning appears very effective -- even when I brush my retainers before putting them in for cleaning, the left-over water shows debris that has been detached from the surface. This is exactly what I want. I don't know what difference the UV light makes but I can say that my night-time retainers that I've worn for 5 months are squeaky clean.During the day I keep my retainers in the empty cleaner where they stay dry and out of the way. This unit does take up some bathroom counter space but it is more space-efficient than rectangular sonic cleaners and doubles as a discreet retainer keeper as well.I gave this five stars because I find it very effective to clean my retainers and no other sonic cleaner is as space-efficient as this one.