ZENIDOG® Long-Acting Collar mimics the natural, calming pheromones released by nursing mother dogs. The calming effect helps dogs of all ages feel comfortable and secure in stressful situations e.g. loud noises, new home, staying alone, Vet visit, training, travelling. ZENIDOG® collar should fit and remain on the dog’s neck continuously for 3 months, except when bathing. ZENIDOG® collar is not recommended for use with hyperactive or aggressive dogs. Consult your veterinarian prior to use. For Dogs up to 10 kg (22 lb). Fits necks up to 15.4 in. (39 cm).