Get consistent performance from your nitrous system. Upgrade your Progressive Nitrous Control System with one of these safety application kits. What these kits do is give you an extra nitrous solenoid and hardware to plumb into your existing nitrous system. They reduce plunger wear in the regular nitrous solenoid, thereby extending their life and reliability. Also, they close line pressure and prevent nitrous from building up in the intake manifold when the ignition is turned off, preventing unwanted damage when the ignition is turned back on.