Advatage for large dogs 10-25kgs is an easy-to-use monthly spot-on. Once the product spreads across your dog's coat, the active ingredient affects re-infesting fleas within 3 to 5 minutes, kills re-infesti g adult fleas within 1 hour and flea larvae in your dog's surroundings within 20 minutes of contact with the active ingredient (in shed skin and hair debris) – breaking the flea lifecycle. Advantage also reduces the incidence of Flea Allergy Dermatitis and controls lice. Advantage works on contact so fleas don't need to bite to be killed. It's safe for puppies of any age and during pregnancy and lactation. Advantage is also water-resistant. Comes in a pack of 4.