Sentry Pro XFT formulas kill fleas in as little as one hour and ticks in as little as three hours. Your dog is also protected from flea eggs and larvae for up to nine weeks. Going somewhere? Not a problem bathe your dog as early as 24 hours after application. Apply monthly for best pest-control results. Each package contains three months of protection for your dog. Available: 11-20 lbs. dog 21-39 lbs. dog 40-60 lbs. dog Over 60 lbs. dog Size: 21-39 LB. Type: Flea and Tick.