Don't bother. Sure, it might blast a poppy seed out from between your teeth, but really, it's not that impressive. It doesn't hold a charge and it's an awkward size. It doesn't fit in the sink to fill up the chamber ... I have to fill a glass then pour the water into the chamber. There is no control over the jet strength, and there is lots of water left in the compartment even after it stops blasting. I always have to turn it upside down to empty it into the sink so the water doesn't stay in there and grow animals. I've taken to storing it upside down in my robe pocket to avoid the standing water. Really, kind of gross contraption now that I think of it. Can't get it really clean. I've used way better oral water jets before. Time to get a better one.