Instruct: Classify Amazon reviews into positive or negative sentiment
Query: Works great

These are are part of the Littermaid self cleaning litter box system. On the one hand, it irks me that these filters are not included with the replacement tanks. But on the other hand, they absorb odor well, so at least you're getting your moneys' worth. The whole system works well. Without these filters, the system works okay, but using these filters with it really makes it go from good to great. No smells at all when you're using these.