This is a model for finding the angle of a windshield wiper. The angle of the wiper is important for reducing noise during cleaning. This angle should be as close to perpendicular as possible to ensure the least chatter and a smooth transition when switching wiping directions. This point is marked with a peak on the scale at 0 degrees.

This is intended to fit the hook-type wiper connection, probably close to the ISO 9259:1991 hook standard. It hasn't been measured, but it looks about right :)