Using these LitterLocker Design Plus litter refills is easy. First, open up your LitterLocker cat litter bin system. Then, take out the old refill and put the new one in. Make sure it's placed properly so the Air - Seal technology can work its magic. When it comes to replacing the refill, you'll know it's time when the odor starts to escape a bit. Remember, for one cat, each refill should last up to 2 months. To keep your LitterLocker system working well, clean it out occasionally. Just wipe down the inside with a mild cleaner. Also, store the refills in a cool, dry place to maintain their quality.