Cat's Best Original Clumping Cat Litter Using Cat's Best Original will make unpleasant indoor odours a thing of the past, as they will be trapped inside OkoPlus?s organic fibres. This fibre comes from untreated domestic fir and spruce wood, which accumulates naturally in the environmental cycle. Using this wood is a help to maintaining healthy forests. Made from organic fibre, it is much lighter and easier to handle than comparable mineral litter. This in turn saves on transport costs and makes OkoPlus a truly environmentally friendly litter.