Beaphar Flea & Tick Collar For Dogs is a water-resistant collar that will kill fleas and ticks, and prevent further reinfestation for up to four months. Flea killing begins almost immediately, but it may take several days for the active ingredient to spread throughout the entire coat. The collar is 65cm long and will fit most dogs. Suitable for dogs from 3 months of age. 95% of the flea?s lifecycle is in the home. When tackling a flea problem, in addition to treating your pet always use a household insecticide, such as Beaphar FLEAtec or Beaphar Extra Long Lasting Household Flea Fogger for your home.