We purchased this to replace the original pump that came with the Drinkwell 360 which we've been using for 4 or 5 years. I see that another reviewer had good experiences with it fitting correctly. I found that it fit OK, but not great. But that could result from many different things in the manufacturing of the water fountain and the pumps. It is definitely louder than the original pump but still quiet enough not to bother anyone. More like a louder "hum." I do find that the noise transmits through the floor so I can hear it in the bedroom (which is in the basement in my case). It is still a good pump and we're glad we purchased it.