These collars uses the same pheromone release system that mother dogs use with their puppies. The odourless pheromones send "comfort messages" to pups which can help calm nerves, offer confidence and provide a strong signal of security and comfort to dogs of all ages. This "On the Go" collar is perfect for outdoor situations like loud noises, dog parks, training, boarding and potential separation anxiety. Each collar provides 4 weeks of constant calming support, and are heat activated so a snug fit is best. Keep the collar on your dog at all times, except when bathing or swimming for the pheromone system to work.

S/M - Fits necks up to 37.5 cm (14.7 in) for dogs weighing up to 15 kg (35 lb)
M/L - Fits necks up to 62.5 cm (24.6 in) for dogs weighing up to 50 kg (110 lb)