... refinery Industry Coal Mine Underground Coal Mine, Pipeline, and Explosive Portable Multi-Gas Detector for CO, H2S, O2 and LELNatural diffusion ... and clear indicationCompact design, easy carryingHigh strength engineering plastics and compound anti-slippery rubber; high strength, water-proof, dust-proof and ... 2 yearsExplosion-proof grade: Ex ibd IICT3Protection Grade: IP65 BX616 Portable Gas Detector