For now, I'll describe it: There is a bulge at bottom center with a hole to allow passage of the rod. The bulge does not extend the full length of the band, only about 5/8" or so. The whole thing looks (from the front) much like the lines of a camelback mantel clock, as there are smooth re-entrant curves at the sides, it is NOT simply an inset cylinder, as the lower edge of the rod hole is tangent to the line of the inner diameter of the band.