Nitrous Pro Flow's unique Patent Pending bottle mounted high flow filter is a must for prevention of costly solenoid damage and lost races due to debris entering the solenoids, nozzles, and/or spray bars. This filter was designed to provide a minimal pressure drop for maximum flow and to prevent a phase change in the nitrous oxide as it passes through. It replaces the bottle adapter fitting and in-line filter for a cleaner, more efficient package with fewer connections. Fits all standard nitrous bottle valves and available in #4, #6, or #8 feed line sizes. Required for use with all Nitrous Pro Flow systems.