The Balance Harness is a training tool and should be used as part of a training program to reduce your dog's tendency to pull on lead. The Black Dog Balance Harness helps stop your dog pulling on lead - it helps you train your dog to balance correctly on all four feet and not rely on the lead - They learn to walk comfortably without the need to pull. Gently Stops Dogs Pulling and allows Effective Training Control from the Front and the Back, using a Double Ended Lead - the Extra Large is now available as a Training Pack, with a stainless steel shorter lead, see "Balance Harness Training Packs" for Harness/Lead combo deal or Just Connect at the Front, with a normal lead. Easy to Fit and adjust - comfortable and strong. Restores Balance and allows Effective Lead Training. A great Walking Harness, and an effective training alternative for dogs with neck issues, or if a head halter is not appropriate. If your dog is an escape artist, you may also like to consider a Connector Strap as back-up security - they are easily attached as backup security on Balance Harnesses - connected between the Front D-Ring (or Back O-Ring) and clipped to the dog's collar. Measuring for a Balance Harness We size Balance Harnesses by the Girth Measurement of a dog. We also have the Chest measurement available to double-check this too. Don't just try to guess by breed type - there's lots of variation in sizes of individual dogs, so a Girth Measurement will get the right size harness first time.