Fisch FSN-356721 Pen Makers Drill Parabolic Flute design eliminating the need to withdraw the bit until the hole has been drilled through Can drill up to 1350 holes without sharpening European Pen Makers Drill Bits made from M2 HSS High Speed Steel for longer life The full length of the drill bit can be used in a single pass Reduced friction by the shape of the outer flute area makes for faster drilling and less heat buildup for longer life Includes 1 each of 7mm, 10mm,25/64", 27/64" and Letter "O"