A spot on type product for the control of fleas, heartworm and mites. Applied monthly to the skin between the shoulder blades. A very safe and effective product. Comes in the following sizes - Puppies & Kittens (Small up to 5lbs). Medium - 10 -20kg/20-45lbs; Large - 20-40 kg/45-88lbs. Available in both 3 pack and 6 pack.