These bits are ideal for lathe enthusiasts. They are cut in a parabolic helix and deliver a clean hole in one quick pass, which is great for acrylic blanks. Due to the nature of the cut, they are very expensive to buy individually. This $80.00 5 bit set should contain 7mm bits, the letter "o", 25/64", 10mm and 27/64" bits. I wanted the 25/64" and 27/64" first, which cost about $50.00 and are purchased separately, so I figured the set was a reasonable deal at least. I ordered them in May andโฆ