Data storage, temperature and humidity measurement. At the same time, check and measure 1-4 kinds of gases and high-temperature flue gas. High-definition display screen, simulation icon display menu basic functions, built-in pumping measurement. The MS400 portable four-in-one combustible gas detector has a protection level of IP65, can prevent dust and water splashing, and has built-in replaceable water vapor and dust filters. Capacitance 4500 mA, overcharge, over-discharge, overvoltage, short circuit, overheat protection, 5-level accurate power display, USB communication and charging interface, support data export, real-time curve display. Free conversion of multiple units, automatic zero point tracking, multi-level concentration calibration, intelligent identification and prevention of calibration misoperation, audible and visual alarm, vibration alarm, undervoltage, system fault alarm, and one-button recovery of basic functions. MS400 portable four-in-one combustible gas detector is explosion-proof, shockproof, intrinsically safe circuit design, anti-static and anti-electromagnetic interference.