AquaClear Zeo-Carb Filter Insert contains a mixture of ammonia removing resin and premium research grade carbon. Use of the zeo-carb filter insert will remove toxic ammonia, unwanted odors, discoloration and impurities resulting in a crystal clear aquarium. This dual purpose insert gives you the combines benefits of carbon and ammonia remover while allowing you additional space in your filter for other types of inserts. Designed for use with AquaClear 50 Power Filters. Shipping weight: 1/3 lb.