Fisch pen drills now come in a handy five-piece set which includes the most popular sizes. The flutes of a Fisch pen drill are noticeably different when compared to standard drill bit flutes. This exclusive design eliminates the need to withdraw the bit until the hole has been drilled through. With less clogging, better tip geometry and faster chip extraction, the heat created by the drilling process is dramatically decreased. The deep flute shape clears the chips without repeatedly having to back The bit out during the cut. No vibrations or wandering of the drill bit during the drilling process. Includes one each of 7mm, 10mm, 25/64", 27/64" And letter "O".