Air Sentry Guardian desiccant breathers are the next step in contamination control technology featuring stackable cartridges for further extending the life of your desiccant breather. Models are also available with optional isolation check valves for isolating absorbent from exhaust air and filter condition gauges for easy status updates at a glance. G12S1NC Silica 1" NPT 16" Height Valve Yes Gauge No. Product photo is an example and may not reflect specific options on this model.