A regulator is adapted to connect to a gas cylinder, particularly at a location upstream of a cylinder valve, and the regulator may include at least one of a filling slide component, oscillation damper, charge port, and a reset assembly. The regulator includes a body enclosing a cavity, and an inlet passage configured to attach to an associated gas cylinder and an outlet passage configured to attach to an associated cylinder valve, the inlet and outlet passages in selective fluid communication with one another. A flexible diaphragm/bellows is interposed between the inlet and outlet passages. A poppet assembly is located between the inlet and outlet passages that selectively seals with a poppet seat to regulate fluid flow between the inlet and outlet passages.