Prevent impure water from flowing back and contaminating the clean water supply with the Anti-Siphon Backflow Preventer. Required by most local health codes when using a potable, and sometimes non-potable water source for your drip system. The atmospheric vacuum breaker has a 3/4 in. FHT connection which threads onto the hose bibb or faucet; 3/4 in. MPT connection on the other side to attach to 3/4 in. FPT pipe. Removable filter washer blocks particles that can clog emitters. Use the directional arrow on the device to position in the direction of water flow. The Anti-Siphon Backflow Preventer is made of acrylonitrile butadiene styrene (ABS) treated with UV inhibitors.