Yibuy Stainless Steel Guitar Fingerboard Saddle Nut Radius Gauge Measuring Tool Silver for Luthier Set of 4 Handy when you want to check a fingerboard without taking the strings off Practical tools and be convenient to carry out Made of stainless steel which is stable,durable,beautiful and widely used convenient It's faster to use than any ruler, and stays parallel to the fingerboard-much easier than trying to hold a ruler perpendicular to a rounded fret.