Compatibility: Compatible with 95oz/2.8L Automatic Pet Fountains . Please check your fountain model before purchase. Triple Filtration System: Composed of a cotton layer, activated carbon and an ion exchange resin. Effectively to filter hair, heavy metals. Filter Size：Length is about 3.9inch. Width is about 3.9 inch.Thickness is about 0.4inch. Pre-Filter Sponse: Length: 1.5 inch; Width: 1.1 inch; Height: 1 inch. 8 Pcs Cat Water Fountain Replacement Filters : The Pack Includes pack of 4 cat fountain replacement filters and pack of 4 Pre-Filter Sponges. Note: Please soak 5 minutes foam filter before use. Replace filter every 2-4 weeks.