The MicroClean inner core of the 2 piece interlocking system for Sundance 880 & 980 series spas 2009+ (models include Aspen, Maxxus, Optima, Cameo, Altamar, Marin, Cambria, Capri, Claremont, Kingston, Lisbon, Odessa). Do not soak. This filter should be replaced every 3-6 months. Part Number: 6473-164