Smart. Trusted. Best-In-Class. Scepter Marine is your one-source solution for innovative fuel tank technology. Scepter is the global leader in the design and manufacture of innovative and high-quality marine tanks like this 6 gallon Neptune fuel tank, model 08592. Constructed of sturdy seamless one-piece polyethylene plastic for durability. Equipped with Scepter's 2 way vented cap; this automatic air inflow valve system allows air to enter tank during operation and pressure to be released above 5 PSI. Scepter tanks are built to last. Caution: Tank swelling will occur. EPA regulations have eliminated the traditional venting in these tanks. The swelling is a result of the fuel vapor building pressure, because the cap must stay sealed up to 5 PSI.