Fluval Suction Cup for Filters, 30-Millimeter, 4-Pack Y Shaped dog coupling Fits Fluval filter models 104, 105, 204, 205, 304, 305, 404, 405 Also used for Fluval 1 Plus, 2 Plus, 3 Plus, 4 Plus internal filters Includes 4 pieces per blister box Measures 4/5-inch length by 2-5/7-inch width by 4-2/7-inch height