Endure® Sweat-Resistant Fly Spray Stays on and keeps working, even in wet conditions Provides up to 14 days fly control Contains special conditioner that binds to hair shaft - won't sweat off Protects against biting and nuisance flies, gnats, mosquitoes, deer ticks and lice Repels and kills deer ticks that may transmit Lyme Disease Includes sunscreen The only fly spray with RepeLock®. RepeLock® is an exclusive conditioner that binds to the hair shaft, locking in Endure's fly repellency. This unique formula stays active even when your horse sweats or in wet conditions.