High Grade Stainless Steel Connector;Corrosion Proof Oxygen Barrier;Factory Pre-Charged at 15 PSIG;Thickest Diaphragm - Heavy Duty Butyl/EPDM;Strong, Deep-Drawn Steel Construction;Patented Insight Service Indicator Cap;In-Line Models Available in 2.0 through 6.7 Gallon;Suitable for Use in Glycol Applications