Air Sentry Guardian Desiccant breather with isolation check valve and gauge. The Guardian™ is a revolutionary design, incorporating 4 check valves in the top cap and 4 in the base, open at 0.1 PSI.GUARDIAN is Air Sentry's industry leading breather series. The GUARDIAN's casing is constructed from Tritan®, a patented material highly resistant to impact and chemicals with a broad range of operating temperatures. These unique features equate to a longer life for your breather and your equipment.GUARDIAN's modular construction and optional add-on features allow you to customize each Guardian model to your specific application requirements. From the isolation check valve, to its stackable design, from its wash-down cap, or its compound indicating gauge, to the high-capacity HEPA filter, the GUARDIAN will last longer and reduce downtime giving you the flexibility you need to protect your industrial assets.Base Material: 100% Silica GelCartridge length: 12”Ideal for Most Applications. The only desiccant breather series that Air Sentry recommends for diesel fuel applications (not recommended for other fuel applications). Guardian breathers used on diesel fuel applications must be accompanied with an isolation check valve. See Guardian models ending in NC, NG, NGC. Not available in models ending in N.