Pro-fit subby center holder can be used when you do not want a drill hole all the way through. Perfect, for example, when you do not want to destroy the underlying insulation, electrical cables, etc. You must first use a regular center drill and as soon as you get a little grip with the hole saw, you can put on the stubbu center holder and continue your drilling. Fits all Pro-Fit hole saws, 2 steps for hole saws over 32 mm and one step for smaller hole saws Fits HM -multi purpose and Dosfräs Perfect in combination with hole finder Hole in One