Penn Plax 15 1/2X15 1/2 IN Gravel paper BA633 Gravel sheets provide grit for hard-billed birds and aids in digestion. The Paper is made with crushed sea shells for added calcium. The Gravel helps to keep birds beaks and claws trimmed. The Gravel Paper is safe, clean and sanitary. Cubes: 0.0017. Weight: 1.6700 lbs.