re: 1/8" Parting Tool

Hi ken. It is for drilling round pied right through the center. I checked a 1 5/8" piece  of steel and it was within .0005" from side to side. I don't use it a lot but when I need 2 pieces to line up and be able to turn them and line up, I use it...or fit onto a piece that already has a hole through the center..