Land O'Lakes Purina 0044573 Oyster Shell Supplement, 5-Pound 5 Lb. Oyster Shell Supplement Helps Support Healthy and Sturdy Egg Shells Supplement Provides Calcium and Grit Hens That Are Laying Eggs Need A Source Of Calcium To Replace What They Use In Making Their Egg Shells Oyster Shell's Function As Grit To Grind The Stuff These Chickens Will Also Eat