Place the applicator tip through the animals hair to the skin level. On cats, apply to skin on neck at the base of the skull. Spot on applicators are portioned based on the pet’s weight: For small cats & kittens up to 9lb use 1 tube from dark orange pack; For cats over 9lb use 1 tube from purple pack. Safe to use on kittens from 9 weeks of age. Available in 3 and 6 packs.