K9 Advantix (imidacloprid + permethrin) is a convenient monthly preventative for dogs that both repels and kills fleas, ticks, and mosquitoes. Because it repels and kills, K9 Advantix offers a more comprehensive protection against fleas & ticks in comparison to other veterinarian-recommended brands. K9 Advantix stops biting fleas within three to five minutes and kills 98-100 percent within 12 hours. (4 Pack = 4 doses which lasts 4 months.)