Product Description A great little tool for filing and cutting top nuts so that your strings sit perfectly with the action as low as you wish and a price that is so cheap every guitarist can afford to buy one now. Please note this is an upgraded version of the original file where the wire files are now 100mm long with heavier 30mm long cutting file "teeth" If you look at the close up photo of the largest and smallest files you will see that the cutting surface is a series of concentric "grooves" around the file that provide the cut. The circular files fold out from the aluminium casing and include all the following sizes so even if you have a guitar with hefty strings tuned down to Low C this file will cut the string groove for it. 12 round files in the set in the following approximate sizes. 0.4mm, 0.5mm, 0.6mm, 0.7mm, 0.8mm, 0.8mm, 0.9mm, 1.0mm, 1.1mm, 1.2mm, 1.3mm, 1.4mm, 1.6mm Please note this is NOT a professional grade nut file tool that will set you back a lot of money BUT it is perfect for the average guitarist and home builder to successfully file and adjust a few plastic top nuts. Flipping heck its not much more money than the cost of an average top nut itself. File sizes are approximate as measured by me with a digital micrometer. NOTE - this is only suitable for plastic top nuts. It will not cut bone, metal or Tusq nuts, all you'll do is wear out your elbow trying, it is ONLY suitable for plastic top nuts. And once again, I can't stress enough, this is NOT a professional grade tool, its a cheap and cheerful way to achieve the job To be totally honest with you it's actually designed for clearing welding nozzles but is perfect for top nuts as well. The file set also includes a flat file, which I presume is of some use to welders, but I can't see any real use for it for guitarists. I only mention it becuase it's there in the set.