This is a 90 Degree Gusset, Pretty much what you need 20 of, they are relieved for additional clearance yet not enough to adversly effect strength. As always, .25" (1/4) thick. Gussets help relieve the stress of welding by distributing it over a larger area. They add triangulation to an area in need of help (particularly in open areas like door openings) but don't make a bad design better. We limit out cutouts in gussets to keep laser costs down because you might need 30 gussets on a full cage installation, and that adds up real quick. We do make a couple of gussets with a cutout for quick tie in points or where you can clip in a carabiner for a safety line, on these we leave a substantial amount of material to do the job around the openng.