Original Item: The Fire Control Alidade is a hand-held scale used to determine how much deflection is needed to correct fire onto a target.  These are labeled for the 81 mm mortar but can be used with any gun the fire of which can be seen.  The scale is in mils, a circular unit of measurement used primarily by the military to specify horizontal angles.  Instructions are included with the alidade.  The instrument is made of a white polymer.