Bob Martin Double Action Spot On for Cats and Small Dogs Under 4kg with its active ingredient, Imidacloprid. Designed to kills fleas on your pet and targets flea larvae in your pet"s immediate home surroundings. Each treatment will protect your pet from fleas for up to 4 weeks. Its specially developed double action formula kills fleas on contact and will kill flea larvae in your pets immediate surrounding e.g. your Cat or dogs bed area or its favourite spot on the sofa. A quick and effective answer. This pack gives up to 12 weeks protection and can be used on puppies and kittends from 8 weeks of age. Help keep your four legged friend enjoying life.