The Redline Airsoft SFR regulator (Super Fast Refresh) HPA in Airsoft has Evolved. Engines are more efficient and run at lower pressures than in the past. Therefore the demands on the regulator have changed too. With the lower operating pressures and higher efficiencies of modern HPA engines, the regulator must be much more sensitive in order to properly react to the smaller "pressure pulse" of each shot. This is especially true when running a remote hose since the air volume in the hose acts as an "air capacitor" further dulling the pressure pulse that the regulator sees. Failure of the regulator to react properly to this dulled (dampened) pressure pulse can be interpreted by the user as "shoot down" or a "slow refresh rate." The SFR is Redline Airsoft's newest regulator. It combines high sensitivity and a super fast refresh rate with a high flow design. It performs equally well whether powering an air sipping PolarStar "Jack" at 40 PSI or powering an air hungry Daytona gun at 120 psi. It also works with both standard high output and SLP/ELP type low output tanks. The SFR is a fully balanced regulator. Why is that important? Unbalanced regulators are subject to what is known as "supply pressure effect." That means the regulators output pressure is affected by changes to its input pressure. Unbalanced regulators can have a very large pressure change as their supply tank empties. Importantly on some types of regulators, that pressure change can cause the regulators output pressure to rise as the supply tanks pressure drops. That can result in an undesirable situation since any rise in output pressure will cause a corresponding rise in velocity. The SFR's output pressure is unaffected by changes to its input pressure. That means even as your tank empties, the SFR's output pressure and therefore your velocity, will remain unchanged. The SFR also includes a new, more intuitive, integrated tournament lock and an overpressure relief valve. The Redline SRF is 100% made and assembled in the USA