The specially developed formula of Biokat's Classic 3in1 meets even the highest demands. With Hygiene Formula™, our classic features three different particle sizes for fast odor retention, firmer clumps and higher coverage! Products are available fragrance-free or with spring, baby powder and cotton flower scents. Coarse grit Hygiene Formula™: mix of three different grit sizes for fast odor retention, firmer clumps and higher coverage. Less carry out. Clumping litter made from pure natural clay.