He is trying to get registered with this site but is having problems... but here is his response I asked him your questions:
Anyways response to BOB The arms are made from DOM tubing 1-1/4 OD 3/8 wall and are used in jeep comps and also on the jeep long arm kits he makes and are slid on all day, he will upgrade if you want to goto 2"od arms super heavy wall he says but the price is much more expensive and for most trucks driiving around the freeway, rock crawling to their potential, and compared to all the other lift kits available that you might buy these arms are of a way higher class than the conventional lift kit arm and way beefier than the stock arm.
He says hes not concerned with the strenght of the brackets compared to the stock brackets that were holding your old stock arms out of one piece 3/16 thin and these brackets have desert style standoff's to reinforce the holes and are also made of 1/4 thick high grade steel, laser cut, auto cad drawn, and welded by qualified welder. .
Second reply,
The brackets are intended to be bolt on for the do-it yourselfer with the option or recommendation of welding on for added strength, the holes if welded will act as plug weld holes as well if not bolted.
Both brackets utilize thru frame crush sleeve style helpers to avoid crushing frame and keeping brackets secure and in place. .