You just have to cut a slot with a #11 x-acto blade behind the SFG, right at the base thru the wing to the bottom surface. Then slide the flat carbon stock thru and push down while holding the undersurface with a finger. You'll feel the carbon start to push thru and then you have an alignment point. I don't think the SFG's will hold up with out it, but you can try it without. Just makes a nice line up between the 2 SFG's and adds some rigidity so the SFG's don't flex during KE flight. Helps with precision. My 2 cents. Good luck and don't rush thru it. Take your time and do a final CA after you've tacked everything and you've double checked the alignment. I don't think I could have done it without my laser. My eyes are good but not that good! Of course any jig you can make will only make the job easier- when your friends want you to do their Tributes too!!!