Its 1/8 inch and 1/4 inch Disc blades from a Disc Harrow (plow disc). They should not warp. They are all concave 1.5-3 inch deep 12-28 inch in diameter. Using them to build Discos. Basicly a giant wok. Originated in South and Central America. Used for slow cooking over camp fire, I use a turkey fryer burner at home. We use them to cook all kinds of stuff. You weld the hold shut or plug it, grind it smooth, weld handles to it. I usually use big horse shoes on the small ones and 1/2 inch bent rebar for he big ones. Some people weld legs to them to use over camp fire. I usually don't do that I build small stands. That way they can be used on a burner or over a fire. Some people also weld rims around the edge. I have probably 30 disc left to complete. A few are bran new and a bunch are rusted and used. A couple will still need to have a lot of rust ground away but most either have light surface rust. The new ones are powder coated and that's a pain in the **** to grind off it clogs up the pores of the grinding wheels. Makes it take forever. We are going to be giving them away as gifts to friends and family for Christmas as well as donating several to a local boy scout troop.