Spa X01: Spatec Outdoor SPA Filter 301, 401, 601, 701 and 801. Spatec 300/500/750/850: Spatec Outdoor SPA Filter 300, 300B, 500, 500B, 750B and 850B. Spatec 700/800: Spatec Outdoor SPA Filter 700, 700B, 800 and 800B. Remember that the filter has to be changed every 6 months or every time the SPA remains empty