Brain, got to see if I can explain it. The corner knuckle is 3/4" which is the same size as the as the tube and will be flush. The 2 inserts will fit inside the pipe which is 5/8" ID but should fit snug. The inserts are 1.25" long. Hopefully I explained it properly. I need 4, I'm making a custom seatbox tray and doing it this way I'll be able to make exactly what i need. Thanks.
Thanks Ron, I will contact them tomorrow.