Sizes to make practice lugs. The outer tube (the "lug") needs to be .125" larger in diameter then the inner tube and have a .058 wall. So a 1.250" tube with a .058" wall slips over a 1.125" tube. The fit is a slide fit. After light sanding or dremelling to clean i find the fit is just about perfect for brass/bronze. My sleeves are cut to resemble a head lug with one end square and the other cut at a diagonal. I hold it all together with a nail/pin. See attached photo.