The ONLY reason this gadget is getting 4 stars from me is because the lid is not designed to stay open; it's a bit of a fiddle to actually put water in it or empty it after, because you must hold the lid open while you do it. However, in all other respects I am completely satisfied. It's surprisingly quiet, for a device which relies largely on vibration for cleaning. Fill the "tank", close the lid, press the button, it does its thing while you're brushing your teeth or whatever. My nightguard looked and felt noticeably cleaner the very first time I used my Sonic Spa Pro. I also tried using it to clean my wedding ring and some other jewelry, and it worked like a charm. If you're sick of scrubbing your dental appliances, I do whole-heartedly recommend this unit. As mentioned, my ONLY issue with it is that the lid does not hold itself open. That minor improvement would knock it out of the park, IMO.