● No need to change for about 1 week. 1. Anti-microbial agent strongly reduces odors. It absorbs urine thoroughly for a week and can be replaced once a week. The sheet type makes it easy to change without messing your hands. 1. When using a deo-toilet with a beloved cat (weight up to 17.6 lbs (8 kg). Please make sure to use this set of 3 items for a weeks deodorizing and antibacterial deodorizing toilets. This product cannot be used alone.