The plastic black base twists off to allow the two required AA batteries to be inserted, and you can see a thick red rubber border that keeps water out of the battery area. I'm not sure how the vibrations work under the silicone exterior, but they vibrate strongly throughout the toy. With some vibes you can tell that there is a vibrating bullet in the toy, and it mostly vibrates in that one area, but not with big red here. The toy is surprisingly quiet. At the very highest level, it sounds like a cell phone vibrating on a table, but the many levels from weakest to the top are all quiet enough to use in a house with thin walls. There is however, only two simple settings - on or off. There are no intricate vibration patterns, just a steady, constant vibration.