Mixed Bird Grit 25kg. Pettex Bird Grits contain all of the right graded ingredients to maintain good health, aid digestion and increase vitality in all types of birds, ingredients include; Flint Grit - Insoluble and acts as a grinding agent in the gizzard to enable complete digestion. Limestone Grit & Crushed Sea Shells - Soluble and have a high content of Calcium which is an essential element in the diet of all birds. Charcoal - Included for sweetening of the crop. Available in 25kg Mixed Bird (code no. 581), 10 x 2kg (code no.582) and 25kg Pigeon (code no.583).