This is an early NSDAP Parteiabzeichen marked Ges. Gesch. (Gesetzlich Geschützt -> Protected by law).
In good condition, but with a very small chip at the 11 o clock postition, otherwise a very nice hard to find early badge.
It can be dated to the period 1920-1932.
Harder to find than the many RZM badges from 1934 and later!