Compact, multi-gas detector that supports a wide range of substance-specific toxic sensors, photoionization detector (PID) for measurement of toxic VOCs, infrared (NDIR) for combustible gas (0-100% LEL, 0-100% vol.) and/or infrared CO2. Offers automatic calibration, one-button operation and top-mounted three color display. Interchangeable battery packs that provide up to 25 hours of operation per charge or set of disposable batteries. Highly water-resistant housing and built-in concussion-proof boot protect the instrument from damage due to immersion, dropping, bumps and falls. Datalogging and event logging are standard. Optional field-attachable motorized pump uses same interchangeable battery and includes own power supply. Optional DS400 docking station provides automatic “bump” test, calibration, charging and record keeping. Requires 1419-216 demand flow regulator, ordered separately.