Collars mimic the pheromone that lactating mother give off when feeding their puppies. Dogs remember the pheromone their whole life, and when exposed to them via the collar, relaxes and eases their anxieties. Helps dogs cope with anxiety issues caused byseparation, loud noises, trips in the car, holiday stress, excessive barking, destructive behavior and inappropriate marking. Goes where dog goes, unlike room diffusing products. Can be used on all breeds, all age pets and is safe and effective. For dogsand puppies up to 28 -inch neck.