A caliper is a device used to measure the distance between two symmetrically opposing sides. A caliper can be as simple as a compass with inward or outward-facing points.
![150mm Solar Digital Caliper [Silver]](http://ic10.ecvv.com/upload/UserImage/20141112/100x100/150mmSolarDigitalCaliperSilver_6093437a-642f-47cc-8e5b-8da6e7401788.jpg)
