Cats best universal a universal wonder cats best universal is the low cost ecological product from cats best it is made from 100 pure plant fibres from fir and spruce trees creating pellets that have particularly high absorbency unpleasant odours and moisture are bound effectively within these fibre pellets which are sterilised and spore free as well as being compostable and 100 biodegradable this universal litter makes a great litter for a variety of pets and birds such as cats