Metric + FretGuru 2 Precision 8-in-1 Guitar String Action Gauge Fret Rocker Setup and Evaluation Pro Luthier Tool Metric+ [ADVANCED NEW DESIGN SHIPPING NOW] be sure to check out the optional handmade leather case Precise string action gauge in .25mm number increments, and .125mm line increments = super accurate guitar setup! What is Metric+ ? See description below Fret rocker! The 3 unequal length sides are precision ground and polished. Now you can find that pesky high fret without scratching them. Unique, first of it's kind fret height/fret wear gauge in ~.125mm increments. No more fumbling with calipers, straightedges or feeler gauges. Another first - the uniquely designed Nut Slot Height gauge, which has already been a massive time-saver here on the workbench. Simply rest the thin corner in the nut slot - and across to the 2nd fret, then check the gap as it passes over the 1st fret. It's never been easier to zero in on the perfect string height as it leaves the nut. Also, be sure to check out the separate listing for the sweet handmade custom leather case! Double click on the photos for the expanded view.