The Simplifly is a feed-thru fly control. For Horses 300-500 Pounds Feed 2/5 Ounce Per Day, 500-700 Pound Horses Feed 3/5 Ounce Per Day, 700-900 Pound Horses Feed 4/5 Ounce Per Day, 900-1100 Pound Horses Feed 1 Ounce Per Day, 1100-1300 Pound Horses Feed 1 1/5 Ounce Per Day. Product contains Wheat Middlings, Dehydrated Alfalfa Meal, Calcium Carbonate, Sodium Chloride, Calcium Propionate. Size:  50 lb