For Water Resources, and International Filter, Envirotech 5 stage, and other 5 stage RO systems with 2 post filters. Includes all filters, o-rings, and adaptors for a Water Resources 5 stage RO system filter change. keep your RO system at peek performance with quality filters. Detailed instructions included. ROFCTK, Filter change tool kit available separately. 5 stage reverse osmosis filter pack for Water Resources and International filter reverse osmosis systems. Includes 1 sediment, 1 carbon pre-filter, 1 carbon post-filter(canister type) and 1 inline GAC post-filter with 3/8 quick connect fittings (and 1/4" adaptors), and 3 canister O-rings. Works with Envirotech and other 5 stage RO systems with 2 post filters.