This is the Analox 9100-9220-9B Replacement oxygen sensor for EII Portable Nitrox Analyzer and Analox O2EII Pro Portable Nitrox Analyzer Features: Designed for Use w/Analox O2EII Nitrox Analyzer Measure Oxygen Levels in Range 0.1 to 100% O2 Resolution0.1% O2 Typical Accuracy+/- 1% of reading +/- 0.2% of O2 Sensor LifeUp to 4 years Operating Temperature 23AdegF to 122AdegF (-5AdegC to +50AdegC) Sensor Response15 Seconds to 90% of Final Reading Complete w/O-Ring Great Save-A-Dive Kit Item Analox 9100-9220-9B Replacement Oxygen Cell for Analox O2EII Portable Nitrox Analyzer and Analox O2EII Pro Portable Nitrox Analyzer.