Sea-Dog Line - Straight Gas Tank Vent - Black Nylon - 3571001. These Gas Tank Vents provide the needed air flow to maintain proper fuel flow while filling and during use. Vents compensate for changes in tank level due to consumption, as well as temperature related expansion and contraction. Designed to prevent vacuum build-up during use, which can disrupt fuel delivery they also double as a pressure release valve for the gas tank. Helps prevent fuel spills, blow-back, and ensures fumes vent outboard instead of inside the boat. An integral 5/8" hose barb securely connects vent hose. Constructed of UV resistant injection molded nylon construction.. Specifications:. Material - Black Nylon. A - 1". B - 2-1/8". C - 5/8". D - 1-1/8". Case - 10