Unique prefilter fits any brand of filter or purifier to reduce need for cleaning and extend filter life. Stops all microscopic algae, silt and cysts that prematurely clog the primary filter so that it can focus on the truly tiny bugs that matter. Backflush to clean, filter element is replaceable. Wt. 1 oz. Dimensions: 2 in x 2.5 in 7 cm x 5.1 cm Wt. .9 oz 26 g Stops all microscopic algae, silt and cysts that prematurely clog the primary filter Backflush to clean Backflush to clean PLEASE NOTE: If you live in the state of Iowa, we are unable to sell you any water purification system due to Iowa Department of Public Health Restrictions. We apologize for any inconvenience.