Collars give your pet months of flea and tick protection. Collars with an IGR kill flea eggs and larvae, along with adult fleas and ticks. When you put a flea and tick collar around your pet’s neck, the active ingredients rub off on your pet’s fur, then migrates through the coat along with natural skin oils. Kills adult fleas and ticks for up to 5 months. Kills flea eggs and flea larvae for up to 5 months. All sizes.