Neewer String Action Gauge Ruler Guide Setup Guitar Measuring Luthier Tool Material: Stainless steel. Convenient , pocket-sized ruler. Guide for setting the action on any stringed instrument. 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. The gauge features a progressive string height scale: simply slide it across the frets and read the measurement under the string Please Note: Guitar NOT Included!