As with superflashes, radbots are not necessarily water proof. I have used multiples of each for years and in at least one instance both products have succumbed to moisture getting in them. I usually use one on seatposts, right under the saddle, and one on the back of racks. The lights on the racks get the most exposure and those are the ones that have had moisture build up in them. I ride year round regardless of precipitation conditions and one bike always sits outside at the train station, exposed to the elements, during the day.