Washable Granules™ satisfy a cat's need to dig and cover. Cat-safe, cat-comfy Granules never need changing, just replenishment. Each box lasts 4-6 months. Dust free, non-toxic combination of natural and synthetic biodegradable materials. Degrades in Septic Systems within 9 months. 5" x 10" x 2.5". Box weighs 3.5 lbs.