35mm Nickel Electroplated Diamond Donut Burs best Point Bits

Nickel electroplated diamond grit 80# 240# and 320# donuts best burs. Designed for to grind simple and quick a donut. On the top are holes which allows water flow trough to keep the working surface well and properly lubricated. Step one, drill the middle hole, step 2 use the donuts tool, the middle hole who you drill before will you guide.Shank size 6mm, best in use with drill press.