-Box show signs of shelf wear and has been opened, but actual product (6 doses inside, are sealed) with instructions included. (See photos) Advantage II Large Cat is a leading brand in cat flea treatment and prevention for large cats over 9 lbs., at least 8 weeks of age. Vet-recommended, easy-to-apply monthly topical treatment – no hard-to-swallow pills, no prescription needed. Delivers total flea protection – kills adult fleas, flea larvae and flea eggs through contact. Same-day effectiveness – kills fleas within 12 hours of application and keeps working for 30 days. Fragrance-free formula, waterproof after 24 hours of application.