Attwood Marine - Fuel Tank Vent - Flush Mount - Straight - 660313. On the exterior, they have a smooth edge over the competition. There is no protruding cap to cause damage- or be damaged by- hull bumps or scrapes. Cap unscrews with hex head wrench for easy cleaning of filter and pressure testing of entire fuel system. Includes two silicone gaskets.. Features:. Type - Straight. Hose - 5/8" Inside Diameter. Max Hull Thickness - 7/8". Hole - 1-3/8". 316 Stainless Steel