Based on full-size electrochemical cell, Model G20/G40 monitors 1-4 gases, including CO (0-1,000 ppm), Cl (0-20 ppm), ClO2 (0-5 ppm), combustibles (100% LEL, 0-5% v/v methane), HS (0-100 ppm), NO (0-100 ppm), NO2 (0-20 ppm), SO2 (0-100 ppm), and O2 deficiency (0-25% by volume). Flashing LEDs, LCD, and 90 dB audio alarm warn upon violation of setpoint; available setpoint triggers include reading, time-weighted average, or short-term exposure limit. PC running bundled software uploads max 28,000 records via RS232. Menu-driven screens in English, Spanish, or French simplify use. Monitor resides in rugged IP 65 enclosure; runs on 10 hr NiMH battery; and carries UL, cUL, and Cenelec approvals.