Anyone used this in a build?

SFI DOOR CAR SPECS REVISED - Nov. 5, 2012: The SFI Specs for Full Bodied Car Roll Cages have been revised, effective November 5, 2012. The revised versions are designated as SFI Specs 25.1F, 25.2A, 25.3A, 24.4A, and 25.5A and are immediately available from SFI for use by sanctioning bodies and chassis builders. The extent of this revision is that Docol R8 steel tubing is now allowed as an acceptable structural material for roll cage construction. This addition comes after an extensive engineering review by SFI and the pertinent technical committees. The Docol R8 steel tube dimensions (outside diameter and wall thickness) are the same as those required for 4130 steel, therefore it is not necessary to purchase a new copy of the revised SFI Spec document if you already own the previous version.