Uniweld G4S - 2 Inch Gauge, Pressure Range (PSI) 0 to 200, Smallest Graduation 5 PSI, Accuracy (-Percent) +/-3-2-3 per A.N.S.I. B40.1 Grade B, Gold Steel Case, 1/4 Inch NPT Brass Bottom Mount Connection. Oxygen cleaned welding gauge per (A.N.S.I. B40.1) suitable for use with oxygen, nitrogen, fuel gases and medical equipment which are non-corrosive to brass or bronze. Recommended Part No. GB20S 2 Inch Protective Rubber Gauge Boot. Recommended for use with compressed gas regulators.