The LitterLocker II Refill pack contains four refills designed exclusively for the LitterLocker II. Each refill will last an average of two months with one cat. Each bag features a multi-layer film that locks in odors. The LitterLocker's handle closing system also ensures that the bag remains airtight once soiled litter is in the bag. When the bag is full, just open the LitterLocker, cut the bag and dispose of it. Then you simply pull more film from the refill, knot the bag and pull it to the bottom of the bin. You are now ready to use the LitterLocker again.