Eshopps Filter Sock 300 Micron Rectangular - 3 PackEshopps Filter Sock 300 Micron Rectangular 3 Pack Micron filter bags provide excellent mechanical filtration, which helps reduce the amount of ammonia producing organic matter in your aquarium. They also help prevent larger objects such as sand, crabs, and snails from damaging pump motors. Add these Eshopps filter socks effortlessly to any existing sump.