The W225 series is our best seller as it comes in 8 different scents. Its liquid absorption capacity is high and clumps very well due to the unique shape of the granules, they are small and circular, forming a ball in the litter which makes cleaning the tray easier. Proving to be, cost effective and long lasting. Its clumping is round like a snowball rather than being flat as compared to other products. Its liquid absorbing capacity is high.