The NEW Preventic 6-pack gives you the convenience of 18 months of protection and you save money as well. The PREVENTIC Tick Collar by VIRBAC is the only tick collar that detaches and kills ticks effectively. Each collar is effective for 3 months and is a good complement to Advantage or PROGRAM flea control when tick protection is also required. Recommended for use on dogs/puppies 3 months and older. DIRECTIONS: Place the collar around the dog's neck, adjust for proper fit and buckle in place. Cut off and dispose of excess length. The collar must be worn tightly enough to contact skin and so the dog cannot remove it.