I don't have one but my research indicated Quartz, Ceramic, Stainless Steel cell,(metal in the path of ozone) for that kind of money you can actually get medically certified unit, the EXT50 from Longevity.(no metal in the ozone path) The longevity machine has all glass cell so can be used with blood as where WPS-400 is not medically certified. And lifetime warranty. Also I don't think there is a way to meter the output accurately so you kind of have to estimate, which is unacceptable in my opinion. Hopefully someone who actually has one can verify that? Am just going by literature. You can call them and verify all the above if you like. 615-337-8611 Good luck and warm regards.

Here's a good thread to check out:

//www.curezone.org/forums/am.asp?i=986969