Wuapu offers silica sands that absorbs liquids. We recommend to use this type of sands because it absorb odors really graet and they are perfect for litter boxes located indoors. We suggest to pour the sand into the litter box till there is around 3 cm thick layer because of the thickness it is more reliable that the smell of your cat excrements is going to be absorbed. You have to remove the poop from the litter box daily. Very good product.