1 1/2″ ABS Pro-Vent Anti-Siphon Device

1 1/2″ Black ABS Pro-Vent Anti-Siphon Device. 1 1/2″Male Threads Sink or tub draining slow? Odors at washing machine, bath or kitchen sinks? You may have a defective anti-siphon device. Installs easily and quickly without special tools. With just a pair of pump pliers, unscrew old vent and replace with new. Pipe dope or thread seal tape required. Saves you time and money. You get the same trap-seal protection as with an extended vent line to the outside, but without the unsightly vent pipe to conceal and without the possibility of roof leaks.