VEVOR 3L Ultrasonic Cleaner with Heater & Timer - 200W Heating & 120W Ultrasonic Power for Jewelry, Glasses, Watches, Dental Tools - Professional Digital Lab & Home Cleaning Solution for Delicate Items

3L model . Found the reason some people complain about smoke, well part of the reason. I thought the bottom panel looked like it had clear plastic on it like the lid has blue plastic. I tried to peel it off, but I couldn't because there wasn't any plastic on it. I thought maybe, I just wasn't able to peel the plastic. Being the OCD Mr fix-it man that I am, I decided to void warranty and remover the bottom panel, and heat it with a heat gun, to maybe help remove the plastic. As I said earlier, there ended up not being any plastic, BUT the heat gun revealed some spots on the metal. As you see the spots in the pic, those spots didn't show up until they were heated by my heat gun. My best guess is it is some sort of oil residue from the machinery cutting the holes in the panel, like cutting oil machinist use. It could possibly be something else from the parts above, that maybe dripped something on the bottom during manufacturing. It is not from use, because I took it apart before I ever used it to see why people said it was smoking. Now the good news, it didn't smoke at all. I'm not sure if it was because I already burned the mystery stains off or some other reason. I did notice that the instructions warned more than once to unplug when done, and to also make sure the outlet used to plug it into, has ground. For those not sure how to do that, you can buy an outlet checker here on Amazon. An outlet checker simply plugs in like everything that plugs into an outlet, and let's you know if hot, neutral, and ground are wired correctly. It's a good idea to check all your outlets with such a device. I suspect some of the bad reviews may be the result of using bad outlets. For those wondering about minimum water level, the manual says simply, be sure there is enough water to completely cover whatever you're cleaning, and no more water than the maximum line in pan. It also warns about using no water, which I also suspect some of the bad reviews may be because of that. All that said, it actually works great! Wish it came with the ability to switch from Celsius to Fahrenheit. I ended up printing a conversion chart. I got this for my partials dentures mainly. Before this, I bought the highest rated crappy plastic magnsonic brand, it was horrible. I don't know how it has so many sales and good ratings. It literally melted the epoxy holding the transducer to the pan, then fell down and melted the plastic housing. So if you're looking at that one, or this one, spend a few more bucks and get this one. This Vevor 3L is hands down the best for the money . Last but not least, just my opinion, use distilled water, it has zero particles , just pure water. Don't use tap, bottled purified/drinking water