Forespar Vented Loops, Part No 903018

Made of black non-corrosive material. Install in inlet and discharge plumbing and position so they remain approximately eight inches above the waterline at any angle of heel or trim. The one-way valve in the vent fitting allows air into the loop when a 
vacuum is present caaaus by a siphon condition and closes when under pressure.

O.D. : 1-1/8″ with Valve