These are some of the simple things that really come in handy when tying it all together. They will really add strength where you need it without adding unneccessary weight. Many will use them with the "V" edge down when using a MIG for easy penetration, I like them flat when I TIG for a clean, tight presentation thats just as strong. These are 1020 mild steel but 7/32" thick so no need for Chromoly and if its not going to be heat treated why bother anyway. They are available with a 3/4", 5/8", 9/16", or 1/2" holes, they are 1 1/4" in overall diameter and the apex of the bevel is 15/16". The price is 6 for $10....