NOS Purge Valve Kits are designed to release nitrous at the solenoid to let trapped air or gas vapor nitrous escape from the feed line for instant and consistent nitrous injection. This valve kit eliminates the lag time caused from vapor accumulation in the supply line. This can help with more consistent track times and a lower 60 foot time. These black kits are available in 4AN or 6AN sizes and include a solenoid, filter, push button, fittings, wiring, along with instructions. Nitrous Bottle Purge Valve for -4AN Line