The display, markings, and thumb wheel on these calipers are positioned for comfortable left-handed use. They come with a calibration certificate traceable to NIST that states they've passed a test for accuracy. These calipers have zero-position memory, also known as absolute (ABS) positioning, which retains the measuring position when the calipers are turned off. A zero-set button allows you to start measuring at zero when the jaws are open. They have SPC data output, so you can transmit your measurements to your PC.