Plain steel. 2.9 gallon XL King Tank. Approx. dimension: 16" (40.6cm) long x 11" (27.9cm) wide x 8" (20.3cm) deep. Sold as one-piece upper shell for one tank. This is the exact same gas tank shell Paughco uses to produce their fuel tanks. Now you can do the same; and modify it in the manufacturing process at will; enabling you to build your own one-off gas tank; in a perfect design-balance with your bike. Note: Sold as upper shell only. Tank components as tunnel; gas cap bung; petcock bung and tank mounts are not included and must be purchased separately. Note: It is advised to pressure test; seal and test fit all tanks before tanks are painted and installed.