Product review (4 stars): Exactly three inches in diameter
This is the splashguard, baffle that fits Sinkmaster, Whirlaway, Waste King, and probably everything that uses the EZ-Mount system by Anaheim Mfg. Do not confuse this with the "Universal-fits most disposals" one that hardware stores sell. Those are 3 1/8 to 3 1/4" in diameter, and they're too big. Won't fit. Looks the same but a little bigger, and it won't fit. This one will. It is exactly 3" in diameter. If your old one is pretty worn out, you will be amazed at how much quieter it will be when you replace this simple, no-tools-necessary part. I only knocked off a star for the price. This would still be a very profitable item at half the price.
My disposal is a 1/3 hp BoneCrusher that I paid $23 for probably 12 years old.. We run it a couple times daily, but with really light loading.
The trick to disposal longevity and drawing a blank stare when someone asks if you know a good drain cleaner is to use this sequence for food disposal:  Turn on cold water in the disposal-side basin. Turn on disposal. Slowly add food to disposal, making sure plenty of water is going into disposal. About 10 seconds after you're done disposing, turn off disposal. Let water run another 10 seconds.