Cateco Aerator Replacement Mesh Pack for Cat Litter Box - Pack of 2A vital component of the Cateco litter box's Convactive technology, the Aerator is designed to keep litter in the Cateco's litter box upper section while letting air and moisture flow. Each pack contains two units. Use these replacements in the unlikely event that you need to replace a damaged Aerator or if you simply want to make your Cateco litter box aeration system like new!