K9 Advantix II helps defend your dog against fleas, ticks, mosquitoes, biting flies, and lice. Simpler than a flea collar and troublesome pills, this vet-recommended topical formula works within 12 hours of initial application, killing adult fleas on contact to stop existing flea infestations and prevent new ones. Once K9 Advantix II is applied, your dog is ready to get right back to the things it loves most. K9 Advantix II pest protection is effective on both indoor and outdoor dogs. Your dog should be at least 7 weeks old and weigh 21-55 lbs. to use K9 Advantix II Large Dog.K9 Advantix II Large Dog is a trademark of Elanco or its affiliates.