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.

I have never heard of it. I did a search and found a link to Japanese steel plate.

But wait........there's more !
http://www.elmia.se/de/subcontractor/Pre...or-drag-racing/

Swedish in manufacture , but no real technical data.
Claims of being easier to weld than CM don't tell me a lot.
I wonder if it has to be tigged ?

Yes it has to be TIG welded
Yes it welds very nicely
No it is not the same as DOM

It does not have to be tig welded. (unless thats an SFI spec)

http://www.aedmotorsport.com/blog/article/docol-r8-tube

http://www.aedmotorsport.com/docs/DOCOL_TUBE_R8__R10.pdf