Wind and Rain Mineral with Fly Control contains the proper balance and ratios of all 14 essential cattle minerals and Altosid (MTH) to reduce fly populations and help restore cattle comfort while reducing the mineral deficiencies of the available forage in a palatable, weather-resistant, loose formula. For best results, feed in the spring prior to the appearance of flies and continued until cold weather restricts fly activity in late fall. | Purina Wind & Rain Mineral with Fly Control | Size 50 lbs