UPDATE 05/17/2016: I have been told and confirmed today that some Harbor Freight and Pittsburgh calipers have a smaller data port and this plug will not fit. These calipers have a gray enclosure and the decimal places are displayed in a smaller font. Will post link to new file when I get the connector made.
This is a plug that you can 3D print and make a cable that plugs into most cheap digital calipers to obtain the value and output it to a serial port. See the video at https://www.youtube.com/watch?v=34IsYgL4cMw for more information.