5160 Spring Tool Steel (Knife, Blade) Flat Bar / 2 PIECES / 7 1/2" X 3" X 1/4" +-
The images are typical of what we have. It is all about 1/4" thick but tapers a bit so it may be less than 1/4 at one end and more than 1/4 at the other end.
These were heavy duty truck springs. They have some rust but not very much.