Roll Cages: Chromoly VS. Mild Steel
Also, concerning mild steel roll bar material, there appears to be 2 different types - DOM and EWS according to the S&W site.
http://www.swracecars.com/
(Not trying to promote them. Just a convenient reference.)
EWS is cheaper but @ .134"
DOM is @ .120"
I believe someone told me that EWS is cheaper because its inconsistent in thickness, so @ .134" it will still pass minimum tech specs.
DOM has better quality control and consistent thickness throughout its length, so it can be thinner without going under spec. (It may also be seamless.) Lighter and possibly stronger.
Somebody correct me if I'm wrong on any points.