DeVilbiss HAV511 Air Adjusting Valve with Gauge DeVILBISS HAV-511 High Output Air Adjusting Valve Regulator With Gauge Includes markings for the optimal operating range for the Devilbiss GTI Millennium, and GFG Plus Gun Precise air control at the gun for best, consistent results Impact resistant guage and break resistant lens Lightweight design that fits and professional spray gun