What we have here are some very high quality digital calipers.  As a guitar tech I use these every day; whether it's measuring and verifying string gauges, measuring screw sizes when replacing screws or just  measuring string or fret heights. In fact I use them whenever I need to obtain a "dead on balls" accurate figure.
 
- 6" 150mm Scale
- Fraction, Imperial & Metric Units
- Hardened Stainless Steel Frame
- Precision Ground Steel Jaws for longevity and accuracy
- Accurate to 0.001"
- Thumb wheel
- Battery included