The Frogand its mechanism enables you to adjust the tension of the horse-hair.
Why is the Frog, called a Frog?
Nobody really knows why exactly, however, there are many theories about the origins of the term Frog. In German, the bottom of a horse’s hoof is called the “frosch.”
The “frog” of a horse hoof is a small area toward the rear of the hoof that acts as a shock absorber. Since a bow’s frog is located at the bottom of the bow and also acts a shock absorber, this may be the reason for its name.
Some believe that the frog looks somewhat like the profile of a frog.
Another somewhat far-fetched myth is that the term comes from the last name of the modern day frog inventor, Helmut Gorf. Gorf spelled backwards — Frog. The Frog is also called the Heel, which presents a strong case for the German word origin. (Frosch = Frog)