6540-490 Compatible With Sundance Spa 125 Square Foot Filter Cartridge Used In The Following Models: 2000-2001 Altamar, Cameo, Marin, Maxxus, And Optima. 2000 Capri. 1998-1999 Altamar. 1995-1999 Calypso I And II, Cameo, Capri, Marin, Maxxus, Optima, And Rio. 1995-1997 Corum And Royale. 1997-1999 Montego. Unicel C-8325, Pleatco PSD125U, Filbur FC-2790.