For Model 730 train horn only. Increase air flow and push the Model 730 Demon? to unheard of decibel levels. The Ultra BlastMaster? provides everything you need to add an additional two VX6003 solenoid valves to your Model 730 Demon?. Adding two more solenoids allows each trumpet to have a dedicated air source for dramatically increased flow and a train horn that will push your Demon? over the edge.