★Provides 8-weeks of continuous flea and tick prevention. ★Flea and tick collar for large dogs works through contact, so fleas and ticks do not have to bite your dog to die. ★Veterinarian-recommended flea and tick prevention for dogs in a convenient, odorless and non-greasy collar; No need for messy monthly treatments. ★Starts to repel and kill fleas within 24 hours of initial application Flea and tick collar for large dogs also helps treat and control sarcoptic mange and kills lice.