The MANTA RAY FIRE PIT is made from one quarter inch (6.35 mm) thick steel. The sturdy construction assures you of having this functional art for many years to come. It has an iron oxide patina finish on the outside that will darken a little with time, then become permanent. The inside is coated with a high temperature resistant paint and has a rain drain in the bottom. And on top of all this, it is Made in the USA. Each piece has a brass plate with its unique number. No two pieces carry the same number. This assures your fire pit's individuality.