... oxygen concentration without benchmark gas by adopting conversion ion current with the world advanced technology as measurement principle. It ... consumption.2. Features * New pattern, long-life, conversion ion current tester with fast response and high sensitivity* Concise menu, simple operation ... 0-10ppm, 0-100ppm, 0-1000ppm, 0-25% O2; auto-rangingAccuracy: ±0.5ppm in the range of 0-10pppm; ±1ppm ...