Beaphar Dog Flea Collar Plas Mix Proven to kill fleas and ticks for up to 4 months. During this period the collar continuously reviles diazinon (slowrelease). The diazinon is distributed over the skin of the animal. Diazinon has a non-systemic effect; it does not enter the dog’s blood circulation. Fleas on the skin of the animal come in contact with the diazinon and get killed. The activity of the collar is not affected when getting wet, so it is not necessary to take the collar of when it rains. Suitable for dogs with a neck circumference of 65 cm and for puppies over 3 months of age.