Honestly I'm not really sure, its some type of metal siding. The only reason I want to paint it is because It had some rust along the bottom edge which I removed filled and primed. So far I have replace both axles all springs, rear bumper, holding tank supports, all gas piping underneath trailer, and I removed rust from and primed and painted the frame. Its in great shape now, but it needs some fresh paint. I have a sprayer and all the equipment, I'm just not sure of what type of paint I should use. Any advice you may have would be very helpful. Thanks