|The ATS Digital Protractor is an innovative measuring tool that provides an immediate, digital reading of all angles in a 360 degree range. It provides absolute measurement as well as relative measurement, making it ideally suited to measure aileron deflection, flap movement, and propeller pitch. The 2.75" wide by 1.50" high LCD screen display remains upright to view at all angles. This Self-calibrating unit can convert between angles and slopes; the machined aluminum frame is for durability. This unit is accurate to within .05 degrees of level or plumb. Includes sturdy carrying case with a belt clip.|
These have internal calibration so they can be calibrated in the field as needed.