*All Restek canisters are originally equipped with high-quality Parker Hannifin diaphragm valves. Each valve is helium leak-tested to 4 x 10^-9cc/sec. The all-stainless steel construction eliminates contamination and withstands temperatures from -100°C to 250°C. All valves have 1/4″ compression inlet and outlet connections. 3-Port valves also include an 1/8″ female NPT port for a gauge.