This 401 series gauge line is a competitive line of ammonia gauges, designed with the original equipment manufacturers in mind. Available dry, glycerin filled or silicone filled, these gauges are suitable for use on most ammonia refrigeration systems. These gauges are liquid fillable. The liquid filling helps dampen the effects of pulsation and vibration, while also perpetually lubricating the movement (and keeping contaminates such as dirt away from all moving parts) which will extend the life of the gauge. Also the case and connection are welded preventing possible leakage at the bottom of the case. Although these gauges are the best mix of quality and price we also stock a full line of ammonia gauges available in various dial sizes, connections and case designs.