I bought these bits to carve dados into a cabinet I'm building. The package was delivered on time and I was delighted to see the beautiful wooden box that the bits are stuck in. With excitement I quickly made a jig for my fixed base router and tried a 1/2 inch bit on a piece of scrap MDF. The bit cut a clean pipe but it didn't fit. Then I realized that the bit sizes are slightly smaller than 1/4, 1/5 and 1 inch to match the thickness of the plywood. As advertised, it works flawlessly on plywood. If you use MDF, you will have to resort to other means.