The SI rib racks are chrome plated steel. Personally, I'm not a fan of cooking ribs turned up on their sides. Makes sense, if you have to smoke a lot at one time, but I believe the quality suffers. The best ribs are laid out flat, bone-side down. Two reasons: The bones shield the meat from the heat below, and the rendering fat doesn't drain off of the meat (self-basting). Just my 2¢...