There are literally hundreds of reverse osmosis systems that utilize the "time-proven" sump-type design with the standard 2-1/2" diameter x 9-7/8" length cartridges.  If your system looks like the one to the right, it probably utilizes our standard 5-Stage filter pack.   If it looks like the one to the left, it probably uses the 4-Stage filter pack.  A few of the brands that are identical are the following: APEC,  Flowmatic, Goldline,  PurOLine,  TGI, US Filter, US Water, Vertex, Water Factory, Watts, Watts Premier and others.  If you have questions, please e-mail us at info@uswatersystems.com or call one of our water experts at 800-608-USWATER.