Custom RO ET 6500 6 Stage Reverse Osmosis Replacement Filter Pack Made specificaly for the older model Envirotec(TM) ET 6500 6 stage reverse osmisis with mineral enhancment. Will work on other 5 stage reverse osmosis systems with the added benifit of adding minerals back into the water. The 6th stage filter charges the purified water with benificial minerals. includes a 1micron sediment filter, a .5 micron Carbon block filter, a ECT post-carbon filter, a GAC post filter(inline) and a Calcite post charger. Includes the service manual "How to Service Your Reverse Osmosis System" by Dionicio Porras. Service your RO like a pro!