Unlike some guide sets, the drill shank diameter required for guidance is 12mm. I have a good Freud-Forstner tip to use with a kit instead of a cheap tip. I have yet to try it, but it looks well made. Stay tuned for performance updates!-------------------- And Update #1: The Forstner bit that comes with the kit is mediocre at best. If you're making more than a few doors, a little is better. The Freud bit I have cuts holes cleaner and 5x faster than the bit that came with it. I'm leaving my rating at 5 stars because at this price point you shouldn't expect a $30 beat to be included. The kit seems to guide the bat well. Attach the guide to the workpiece on either side of the center hole. The depth stop must be set after the drill has been inserted into the guide adapter. DAMHIKT. ;-) All instructions are clear and concise. At least I assume they are written entirely in Chinese. The mounting screw guide holes are positioned correctly for the Blum hinges I use. The set is very well packaged.