Insta O2-A PPM Sensor – Replaces Teledyne InstaTrace-CO2 B73016 sensor. AST Model Insta O2-A is the only sensor with same form-fit-function as Teledyne Insta Trace-CO2 sensor, no spacer needed. Proprietary gas impermeable membrane in front of Insta O2-A protects sensing cathode from exposure to high level of oxygen in air during installation. During installation, sample gas continues to flow thru sensor housing. After installation, protective membrane is automatically punctured inside of sensor housing and the sensing surface sees nothing but O2 in the sample gas. This speeds up sensor’s recovery and sensor stabilizes with actual oxygen in sample gas in just a few minutes. Insta O2-A is ideal for measuring oxygen in gas streams containing CO2 gas. AST Insta O2-A is designed, developed and manufactured in the USA.