The Woodford NIDEL® Model 34HF and 37HF anti-siphon vacuum breaker is designed to protect hose connections from contamination where temperatures do not go below freezing. Uses include laundry tubs utility sinks boiler room hose bibbs and outside hose bibbs in non-freezing areas.

Single-Check ASSE 1011: 34HA standard on Model 25 and 65; 34HF standard on Model 24 43 44 45 46 74 75 and 84
Double-Check ASSE 1052: 37HA standard on Model 67*; 37HF standard on Model 76 79 and 86 * Converts Model 65 to Model 67

Integral Devices:
50HA replaces VB222 and is standard on Model C22 B22 27 and 30
50HF standard on Model 26 Y2 H34 B26 and Y95

Have you taken your hose off had a spray-back of water? UPGRADE the 34H series to a 50H series to protect from spray-back! 
The Woodford Model 50 Auto-Drain Double Check Backflow Preventer is the first ASSE 1052 Approved automatic draining double-check backflow preventer. When a hose is removed from a Model 50 equipped wall faucet or yard hydrant two linked but independent checks move as one to open a path through the valve allowing water to drain completely and prevent freezing.

NOTICE:These products as with all 1011 1019 1052 and 1053 ASSE listed devices are not to be subjected to continuous water pressure. Replacement is recommended every 3-5 years. After use turn device to open drain vents or faucet may freeze and burst.