They absolutely are not stainless. At least, the one I have isn't. My tank is pure chinesium grade mild steel. The fuel cap is the only thing "stainless" on the whole thing as far as I can tell, and it's a 400 grade from what I can tell because it still has magnetism, just not quite as strong as the tank.Well ya learn somethin' everyday if you pay attention. I guess we are to assume these tanks really are made of somekind of stainless. At least we have the hope of them not rusting.