Tetra is a low cost four-gas monitor with one button that turns the instrument on, off, and resets the alarms, so training is not an issue. Tetra can be configured with any four gas sensors. Standard four gas detector includes combustible gas, oxygen, carbon monoxide and hydrogen sulfide, but others like chlorine, sulfur dioxide, ozone and nitrogen dioxide are readily available as an option. If gas is detected, a wailing multi-tone siren is triggered together with ultrabright flashing red and blue LEDs. Ship wt. 1 lb.