SODIAL(R) 3.25" 80mm Brass Vernier Caliper Gauge Sliding Gem Bead Tool Jewelers Inches Ruler Material: Solid Brass Metal Precision sliding brass gague measures up to 3.25" (80mm) in increments of 1/16" (1mm). Vernier Design will measure inside and outside of object. Easy to read numbers Ultra precision and effortless operation