These mounting rings are made for either flat top or arched top guitars in the most commonly used colors.
Low Arched:
This is a short plastic humbucker ring with an arched raduis, designed for usage in the neck position arched or carved top guitars. This mounting ring is not an exact Gibson® spec replacement ring. It has slightly larger exterior dimensions with an overall (top and bottom) arched design and slightly different mounting hole locations.
Low Arched: