The Combo Valve offers great operator safety, unmatched performance and rugged durability. A Combo valve is part of a pressure release deadman system. Fast response time. Eliminates high maintenance cost of using dual valves. Easy to work on – the Combo valve can be rebuilt in under 90 minutes. Pressure hold systems are also available from BlastOne. Pressure release systems are very simple systems. Consequently very reliable. Pressure hold systems do not depressurize when the dead man handle is released. This is a major time-saver.