The Mooney Series 22 Pilot is a stainless steel, modular design which provides multiple regulating systems; pressure relieving, back pressure, standby monitor, and working monitor mode for the Flowmax HP. The Series 22 Pilot must be paired with the Type 27 variable restrictor which provides adjustable system gain, stability, and response. The Type 27 variable restrictor features a built-in check valve to prevent damage to diaphragm if the regulator sees high back pressure.