The Beaphar Flea & Tick Collar For Dogs is a water-resistant collar containing the active ingredient dimpylate, to kill fleas and ticks on your dog and prevent their return for up to four months. The collar is 65cm long and can be adjusted to fit most dogs. The collar will take effect almost immediately, but it may take several days for the active ingredient to spread throughout the entire coat. Suitable for dogs from 3 months of age. 95% of the flea\'s life cycle is in the home. When tackling a flea problem, in addition to treating your pet, always use a household insecticide, such as Beaphar FLEAtec Household Flea Spray or Beaphar Extra Long Lasting Household Flea Fogger for your homeect almost immediately, but it may take several days for the active ingredient to spread throughout the entire coat.