The easy-to-use refill is only suitable for use with Beaphar CaniComfort Calming Diffuser. Beaphar CaniComfortcontains a copy of the naturally produced Dog Appeasing Pheromone, which is instantly recognisable to dogs. It is naturally produced by the bitch when she nurses her puppies, and gives a continuous and reassuring message to let dogs know that this is a safe and calm area for them to be in. This can be incredibly valuable when bringing home a new dog, helping them settle quickly into their new routine. Each refill is effective for up to 30 days.