Handy little gauge for measuring wire and sheet metal gauges in decimal inches, gauge, or mm. Sizes from gauge 34 (0.16 mm) to 8 (3.26 mm). The way to use this with wire - poke the wire through the hole - then slide out through the slot - the biggest slot it will fit out through is the gauge. Sheet metal needs to be slid into the slot, but the hole allows you to measure a little ways from the edge so that you aren't making mistakes due to filing, burrs, or deburring. Includes handy protective pouch. About 3.25 inches long - so you can carry it with you, and whip it out and talk knowledgeably about the correct wire gauge and look oh-so-professional.