The Thermax Vest has been designed as a walking vest to be worn underneath a harness/collar and to generate warmth via the insulation of your dog's natural body heat. This innovative dog jacket offers your dog unhindered movement, while offering you the convenience of tethering your leash to your dog without adjusting or removing your dog's jacket. Perfect for active dogs and owners, the ergonomic fit of the Thermax Vest ensures your dog can enjoy their daily walk with no limitations.