When ordering a custom harness be sure to provide the correct size, see picture to measure your pet. All Harnesses will be made to be adjusted slightly smaller and slightly larger than measurements provided to give the pet room for weight fluctuations. Measure torso just behind the front legs. the back strap goes across the back from shoulder to shoulder just behind the front legs. and the chest strap goes from shoulder to shoulder to just behind the front legs. Please note this strap does not go across the throat like a collar does.