Looking for a valvee

Is there a regulated valve with gauge? I'm interested in putting an inline Valve on the airbrush air hose. My pump has one it also has a tank, however i am thinking there must be a way to have constant pressure at the airbrush so I would crank up the pressure at the tank to +- 50 psi and the valve I'm looking for would step down the pressure at the pressure level I select, 20 psi+-  I purchased a regulated valve but all it does is show the psi in the tank I can turn psi down but it will not now show the psi I want on the gauge. like 20psi