This is a pair of Dwyer  Magnehelic Pressure Gauges  there is a 2001-C That measure fro 0 to 1.0 in units of .01 , and a 2015-C that Measures from 1 to 15 in units of 1. Both are in good working order. The 2001 needs a plug for the low pressure port on the back. Please see the photos and thanks for looking.