Replaces my old one. This is my second one. As expected, as it aged the battery was no longer as strong as it used to be. Other products out there, and have tried others. This one is good.
The WP-450 is the one solution for me and I believe is more effective than flossing. I have been using it for over two weeks now and I can see the difference and count that my whole mouse is a lot cleaner.