Pronyl OTC Plus Flea and Tick Treatment for Dogs contains the veterinarian-recommended active ingredient that is proven to be extremely effective in killing pests, even after immersion in water. Model: SER-3 Duration of treatment: One (1) dose monthly 3-month supply Options: 0-22 pounds 23-44 pounds 45-88 pounds 89-132 pounds Package contents: Three (3) vials This supplement is for animal use only. Keep out of reach of children and other animals. In case of accidental overdose, contact a health professional immediately. Consult with your veterinarian before using this product. Due to the personal nature of this product, we are unable to accept returns.