US Patent 9368371 Retaining ring having inner surfaces with facets

A retaining ring comprises a generally annular body. The body comprises a top surface, a bottom surface, an outer surface connected to the top surface at an outer top perimeter and the bottom surface at an outer bottom perimeter, and an inner surface connected to the top surface at an inner top perimeter and the bottom surface at an inner bottom perimeter. The inner surface comprises seven or more planar facets. Adjacent planar facets are connected at corners. The inner bottom perimeter comprises straight edges of the planar facets connected at the corners.