Precision made 3-Sided Fret Level Checker (similar to a fret rocker). Made from stainless steel, the thin design and polished straight edges enable close inspection of fret groups and identification of high frets. 
 
The shape is a 3:4:5 triangle with incremental edge lengths of 60mm, 80mm and 100mm. The tool features a 90 degree angle on one corner making it useful for a variety of additional setting up and marking out tasks.