Product review (5 stars): Perfecto-mundo.
Particularly appreciated ConspicuousConsumer1's review; it was spot on.
My disposal is a GE unit circa late 80's and a splash guard with the similar classic Art Deco star-splash pattern which had shrunk almost 1/4" over the decades; this one was the perfect replacement. Don't go for the generic "fits all size" from Home Depot -- yeah that worked if I stuffed it but it folded over and was obviously not the correct size. This is the one that worked for me. 3" diameter is the correct and precise measurement.