... 3.Explosion-proof Intrinsically Safe Automatic Telephone BOZZ KTH106-Z EXPLOSION-PROOF TELEPHONESpecificationsintrinsically safe ,with certificate, coal mine used ,best quality1.AplicationKTH106-Z mining explosion-proof intrinsically ... audio frequency and impulse signal sending.5)with features of explosion-proof, anti-moisture, volume small, weight light, solidity, durability, maintenance ...