This is a high-purity two-stage regulator for more accurate pressure regulation; highly recommended for GC applications. Gas contacts only brass, stainless steel, Kel-F® and Viton®, to assure purity. The first stage reduces tank pressure by about 90%. The second stage uses a stainless steel diaphragm with the lower-pressure gas for sensitive control; the outlet pressure is held constant. A pressure-release valve after the first stage protects your instrument from over-pressurization. The body is made from chrome-plated brass. Maximum inlet pressure is 3000psig. The outlet is 1/8'' compression fitting (may be removed for 1/4'' female NPT).