High flow double check valves ensure fast priming and low-restriction fuel flow to your engine. Compatible with ethanol blended fuels. Engineered low permeation material prevents primer bulb fuel evaporation, saving fuel and money while protecting air quality. Engineered to maintain flexibility and prevent collapse in extreme temperatures. Meets maximum 15 grams/m2/day permeation allowance as demonstrated through California air resources board test TP-512.