4 Gas Monitor: X-4 is a portable carbon monoxide (CO), oxygen (O2), hydrogen sulfide (H2S) and combustible (LEL) 4 gas monitor. It adopts a high strength material shell and imported sensors, with a service life of 2-5 years (LEL, H2S, CO: 2~3 years, O2: 5 years).High Sensitivity: HD LCD screen can display data in real time, with flash, sound and vibration three kinds of alarm, can respond quickly within 30s. 2000mAh high-capacity rechargeable lithium battery can support standby time up to 16-18 hours. No need to worry about battery life even when outdoors.Technical Specifications: Protection class for IP54, waterproof, dustproof and explosion-proof, with five explosion-proof signs (Ex ib IIB T3 Gb); working environment temperature is -20~50; humidity is