First thing you're going to do, take your cutters and cut a couple pieces. To do this, take a look at your underwire. You need to look for a piece that mirrors another piece. This is easier to do if you are cutting from 2 underwires from the same bra. If you aren't lucky enough to have both, cut a piece about 5 inches long and then lay it on the remaining section. Move it around until it kind of lines up. To be a matched pair, these sections have to sit together, so you want to find 2 sections that are reasonably similar in curvature and length. If that isn't exactly clear, check the photos provided, they may help.