Aftermarket replacement filters designed for Krystal Pure(TM) KR15 reverse osmosis systems. Meets and/or exceeds OEM standards for KR15 RO systems, and other systems that require a .5 micron CTO/VOC carbon pre-filter and two 5 micron carbon block post filters. Also includes canister O-rings. Includes the service manual “How to Service Your Reverse Osmosis System” by Dionicio Porras. Service your RO system like a pro!