I have owned my own analyzer for a few years now. But I rarely dive nitrox. I do teach the class though and need it for that. Sensors are an issue. I have replaced mine twice. I check the analyzer against a shop's that I use for fills and since they do PP blending will find out when they are mixing for someone and just go down and analyze a few tanks to keep in practice and make sure my unit is working. I built it from a kit. The El Cheapo is a great little analyzer and fun to build.