Upgrade your Progressive Nitrous Control System with one of these NOS 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 its life and reliability. Also, the safety kits close line pressure and prevent nitrous from building up in the intake manifold when the ignition is turned off. This eliminates engine destruction and unwanted fireworks under the hood when the ignition is turned back on.