These are extended combs for the Gillette razor, allowing you to maintain a slightly fuller beard without having to buy a better razor. The original razor set comes with three smaller combs numbered 1, 2, and 3. This set continues with 4, 5, and 6 (updated to include 1, 2, and 3 after requested). 4 and 6 are shown in the fourth photo above. It's very easy to extend these as well for sizes 7 and above. I hold no claim that these are actually to scale and match the original 1, 2, and 3 sizes that come with the razor, so test them first! Microsoft changed their stl file fixer, so the stl files for 1, 2, and 3 are not fixed (you need to run them through a fixer yourself prior to printing!) Once I can fix them myself I'll upload fixed versions.