Flies are no match for Farnam Endure Sweat-Resistant Horse Fly Spray! This efficient fly repellent was designed with your horse's health and comfort in mind. Endure features a Repelock conditioner that binds to the hair shaft for long-lasting protection against flies, ticks and gnats. The sweat-resistant formula keeps on working in hot, muggy conditions, protecting your pal from insects that may transmit harmful bacteria and lyme disease. One application works for up to 14 days.