Model 591 Series High Pressure Piston Regulators feature a reliable piston design for precise gas control at high inlet and delivery pressures rating up to 4500 PSIG. Like all GENTEC quality products, the 591 Series provides superior performance and safety features. 1/4in SS Comp Tube Fitting, Gas: Hydrogen Methane. Piston-type construction Body and housing cap are machined from class A brass Delrin cap bushing for smooth adjustments Sintered bronze inlet filter 1/4in Stainless steel Compression-Tube Fitting GENLOK Outlet 2-1/2in gauges Weight: 4 lbs Conforms to CGA E-4 standard for gas pressure regulators