The StewMac Precision Measuring Tool Set (Metric) includes 3 of our most popular measuring tools in one convenient package: the Shop Rule, String Action Gauge, and Luthier's Square. These tools are manufactured with impeccable attention to detail and designed to last a lifetime. All 3 tools share the following features: Made of durable (and precise) stainless steel Designed specifically for stringed instrument work Clear precision-etched markings for easy readability Our metric 6-inch Shop Rule includes features such as: Vertical end rules: perfect for measuring saddles, nuts and pickup heights. Centering rule: eliminates guess work when trying to find the center of the neck, bridge, or saddle. Marks are in 0.5mm, 1mm, and 1cm increments, for fast readings and extreme precision. Our metric String Action Gauge is truly a "Swiss Army Ruler" for setup work on any stringed instrument. Features include: Allows for quick and dependable measurement of string height, bridge saddle height, saddle slot depth, fret slot depth, nut height, and pickup pole piece height. Iincludes a progressive string height scale: simply slide it across the frets and read the measurement under the string. Faster to use than a ruler, with the added benefit of always staying parallel to the fingerboard. String height markers are graduated from 0.25mm to 3.50mm. Our 4-inch Luthier's Square includes features such as: The notched inside corner allows it to fit against corners snugly, without any wobble. 4" long, .040" thick precision steel square with a satin chrome finish that allows for pencil marking. Useful for squaring up parts, accurately setting up tools, and endless other tasks around the shop. 1/32"-increments on one side, millimeters on the other.