I bought a cd-2800 on that website named after a rainforest for around $20. Though I reccomend using warm water, about as hot as the sink will get and keeping the lid up as I hear of people having their units break. But I suspect that is due to condensation seeping up into the lid where the switch to turn it on is. So the choice is risk destroying it or more noise polution, if it means anything I probably used it around 100time's (pressed the button that many times, 3min timer) with all the stuff I cleaned with it. So it might be wise to invest another $10 or so into another unit that doesn't have that problem, you be surprised at how useful these things really are once you use it. I've been cleaning parts to my airsoft guns in it mostly and they won't ever get anywhere near this clean by washing it by hand.
Certain things it will destroy such as pearls, and it seemed to have taken off some of the coating on my wooden opinel handle (and made the wood swell for a day due to the water, 3min in ultrasonic). And I heard of it stripping certain finishes off of guns, but a lot of people use it for cleaning firearms you just have to know what your putting in there. So far I've used it on my rough rider canoe (black jigged bone, aka armor hide), kershaw cryo/blackhorse ii, ka-bar dozier, leatherman micra, and probably a few other knives with no ill effects.
And if it comes with a watch holder, it's meant to keep the watch face out of the water so you can clean just the band. If the whole thing is submerged you can destroy your watch no matter how water resistant it is. (I didn't know this till I started looking into this, heck I didn't know these things existed 3months ago.)
Just be sure to not put your hand or any body parts in the thing while it's operating it's very bad for your health to say the least.
