... 100% Vol 1. Summarize GD80 series portable intelligent gas detector adopts the most advanced large scale integrated circuit technology ... method Concentration unit:ppm,%VOL,%LEL,mg/m3 Acousto-optic alarm means:, vibration Working temperature: - 40 ~ 70 ... stopped working, but Is the wording of "screen Alarm" are flashing, if it's electricity shortage, ... with CO, for example) ozone gas alarm (GD80-O3)