The Mahr Federal AA-1-3 Air Probe are used where contact-type measurement is required with 2500:1 Dimensionair Systems. Air Probes are available in Regular Action (counter-clockwise meter movement when spindle is depressed) or Reverse Action (clockwise meter movement when spindle is depressed) and in various ranges. When used with Model 2500:1 Dimensionair, the Meter Dial must be specified to match the Air Probe range (see table in specification sheet). Air Probe and Dial are color coded-just match the color band on the Air Probe to the colored dot on the Dial to be sure that the Air Probe range matches the readout on the Dimensionair. Air Probes are provided with AAD-55 Straight Adaptor for attaching to Air Hoses. The AA-1-3 model has a measuring range of 0.076mm/.003"