Pressure Gauge, 4 in. 304SS Case, 316SS Internals, 3000 psi/bar, 1/2 NPT Male Back Conn, Glycerin Filled. Corrosion-resistant fillable dry or liquid-filled gauge. Vacuum and compound ranges through 0 psi to 20,000 psi. 316 Stainless Steel wetted parts. Cleaning for Oxygen Service O2 is available only for dry or HL Halocarbon filled gauges.