The Reel Diameter Tape™ measures
the diameter of a reel by wrapping around
the circumference. It is calibrated so that
each inch is 3.142 inches long or pi (π)
inches long. This will automatically convert
the circumference into a diameter.
The Reel Diameter Tape™ also has a
vernier, which makes it capable of
measuring the diameter of the reel to .001
inches.