A variable device for regulating the outlet pressure of a fluid from a valve body, includes a pressure-sensing chamber having a wall formed by a resilient self-restoring diaphragm which is responsive to pressure in the chamber. A valve element connected to the diaphragm controls flow into the chamber. Increased pressure in the chamber decreases the flow into the chamber and decreasing pressure increases flow whereby fluid flow out from the chamber is maintained at a desired pressure. The outlet pressure is adjusted by deflecting the diaphragm in a direction to open the valve while permitting a section of the diaphragm connected to the valve member to remain responsive to the pressure in the chamber. An adjustment cover is provided to adjustably deflect the diaphragm and includes a catch mechanism to allow adjustment of the fluid outlet pressures and also retain the device at a desired value. An indicator arrangement may be provided to visually indicate the fluid outlet pressure.