For your consideration, here is a used Insinerator Garbage Disposal Flange Part. It measures five inches from one of the three pointy edges to the other side and measures 2 1/8 inches deep.

It was used but does not have much wear on it. There is a light surface corrosion spot on it. The spot is not on any place that would be visible when installed. The spot is pictured in the last photo. Item pictured is the actual item up for sale and comes from a non-smoking household. (38.957a-1.5hc)