Product review (5 stars): Muffles the "gargling" sound of the Insinkerator by 90% or more!
Worth noting: it does not appear that it would fit my old badger 444. It appears to be made for only the newer "Evolution Series" Insinkerators.

Its removable. The water pools on top of this baffle and acts as a sound barrier.  With an Evolution model Insinkerator and this baffle, the only thing you really hear is that thuds caused by harder food being hit into the blades, and the slight hum of the motor. (Also worth noting, the hum of an evolution vs a badger cannot even be compared, the badger shook my wall! The evolution just hums.)

Works best when the faucet is aimed at the baffle itself, like in the middle of the side, not straight down the hole in the middle.