This is the Nuvair O2 QuickStick Portable Oxygen Analyzer Sensor Air Tester for Scuba Diving Features: Fast response, thermally compensated sensor Completely sealed, water-resistant housing Anodized marine-grade aluminum body-nearly indestructible! No hoses, adapters, or cables required Easy calibration User-replaceable battery and sensor Magnetic waterproof on/off switch to preserve battery life Pocket sized Uses replacement sensor #9510 The Nuvair O2 Quickstick is the first diver-friendly oxygen analyzer available anywhere! Easy to use, effective, rugged, and amazingly affordable - it is equally convenient for non-divers who need a quick and reliable oxygen analysis above water. The O2 Quickstick is designed for anyone who wants the security and convenience of having their own oxygen analyzer without having to pay a small fortune to own one. Operating the O2 Quickstick is as simple as pointing at the tank valve and "shooting" with only one hand needed! Features On/Off switch and the replaceable thermally compensated sensor maintains accuracy levels that exceed dive industry standards. The unit is completely O-ring sealed for excellent water resistance. This is an irresistible buy as one of the lowest priced consumer analyzers on the market! "