High Density Foam Two Minute Installation Long Life This air filter keeps debris from entering your air system. Without an air filter, particles such as pet hair, dust and other contaminants can get into your system and clog up your airlines or worse cause pump damage. Check air filter every 6 months for debris build up. Depending on environment the pump is run in, replacement could be once every few months to every few years. The cleaner the intake air, the less frequent you\’ll need to change the air filter. This is the replacement air filter for the Linear Piston Air Pump(Medo LA-45C) sold by Aquarium Co-Op.