... in subway ,water resources scheduling,shipping ,shipping port ,railway tunnel and other rough area.2 Feature2.1 Shell of the explosion ... telephone is provided with high stability, high anti-jamming capability, and it is up to national standard GB T 15279-20022.6 ... (Each number up to 16 )2.7 Easy for install and operate3.Technical parameterDefend gradeIP67Ambient temperature-40~+70°CRelative humidity≤95 ...