PRODUCT DESCRIPTION: Features: Guitar Nut and Saddle Sander Quality contruction - aluminum body with brass knobs Accomadate both acoustic saddles and nuts Helps sand bottom square Easy to useSanding nuts and saddles by hand is a difficult and inaccurate job. Holding the small piece in your fingers makes it nearly impossible to sand the surface flat and square, leading to bad tone and problems with undersaddle pickups.Sanding by hand also often leads to taking too much off and wrecking the piece. This Nut Saddle Sander is a perfect tool to square the nuts and saddles bottom, easy and fast! Simply put a nut or saddle inside the device and adjust the screws to set the remove amount that you want, sand it on a flat surface with a sandpaper, and in seconds you get the piece squared and flat! It works for the nut and saddle up to 87mm.*Each mark on the adjustment equals about 0.1mm (.004").