This herbal range uses extracts of natural essential oils which offer a safe and insecticide-free alternative providing your cat with continuous protection from fleas and insects. If a serious flea infestation already exists then it is important to first treat both your cat and its environment with a suitable insecticide to kill the fleas and their eggs. The collar should then be worn permanently to ensure prolonged effectiveness. The collar will last approximately four months before needing replaced. For use on cats and kittens from 6 weeks of age. Please read instructions carefully before use.