
I needed the 12mm bit from this kit to drill a 12mm hole in a guitar that already had a 1/4" tail hole. The 12mm cutter made a perfectly even cut (by applying painter's tape to the guitar first) so the K&K Puresound Mini pickup fitted my Martin acoustic guitar perfectly. These bits are great for cutting wood. A step drill is a great way to enlarge a given hole, especially if you want to create a maximum drill size hole. With that in mind, it is recommended that this kit be viewed as a means of creating a 12mm or 20mm diameter hole rather than a means of creating a smaller hole with a tip. Good value for money, not available at my local store. big box store.