Why do they put one in each box instead of putting out a refill at a lower cost? They include only one in the 30, 60 and 90 days supplies so it is obvious they don't wear out in just a few uses. They even include cleaning instructions. The only reason I can see is so they can charge more for a small devise that they probably have made in China for a buck. They last time I checked that fell under the catagory called "greed".