The HVAC/R series is manufactured by Marsh Bellofram, and is refrigeration ammonia gauge that is ideal for use on ammonia compressors, and any other ammonia refrigeration machines. The unit is integrated with a restrictor which guards it from sudden shocks or pulsating pressures. It has a gauging capacity that ranges from 30" Hg V AC to 150 psi, and 30" Hg VAC to 300 psi.