From Website :

‘Enhance your feline's drinking experience with the 10 Europet Bernina Carbon Filters for Cats Fountains Mango, Cascade & Tugela. Designed for pet owners who want to ensure their pets drink fresh and clean water, comes with 10 carbon filters that effectively remove impurities and bad taste from the water. Made of high-quality plastic and available in a sleek white colour, this drinking fountain provides a convenient and stylish way to keep your pet hydrated throughout the day’

This product from Europet-Bernina is perfect for pet owners who want the best for their feline companions. Whether you have one cat or several, this drinking fountain is ideal for keeping them healthy and happy. So why wait? Get the 5 x Europet Bernina Carbon Filters for Cats Fountains Mango, Cascade & Tugela today and give your furry friend the gift of fresh, clean water!

These also fit the Kokoba Cat Fountain.

I have changed the fountain and no longer need these.