Features Kills & repels fleas and ticks Starts working on contact Water resistant For large dogs & puppies with necks up to 25\” Want to learn more? Check out our related GrangeKnows articles The Dangerous Impact of Fleas on Your Dog and Cat\’s Health WARNING: This product can expose you to chemicals including Tetrachlorvinphos (TCVP), which is known to the State of California to cause cancer. For more information go to www.P65Warnings.ca.gov