They will fit about any size front you would like to use, the slot was made long to give you the extra latitude in building. Couple these with a couple of eyelets and you will have a great axle carrier for a 1/16″ axle for RetroPro anglewinder . Made from .050″ thick half=hard brass, they will actually stand on their own on a flat surface. Weighing in a .8 grams! $3.75/pr.