Primer Bulb - 3/8" Inner Diameter HoseThis Atwood Primer Bulb is engineered and constructed to deliver the most reliable priming and long-term leak-free performance. The exclusive three-layer construction prevents collapse under vacuum and prevents ballooning or bursting under pressure. The low-permeation material prevents fuel evaporation, and this bulb delivers 60 percent more output per pump than leading competitors.Features: It is intended for use with a 3/8-inch interior diameter hose Exclusive high-efficiency check-valves deliver faster priming and low fuel restriction (less than 1kPa restriction at 50 liters/hour) Engineered hose barbs and stainless steel stepless clamps ensure leak-free performance This bulb is compatible with Ethanol blended fuels, and it is EPA and CARB certified Quick Guide (pdf)