Weight Pulling Sledding Dog Harness X-back Style Black Large, 21" Neck Circumference Light weight harness made of quality durable nylon webbing. Extended foam-like double wide chest plate padding. X-back style for racing or training in any season, made to last. Available in 5 sizes - Small, Medium, Large, XLarge and XXLarge. This Harness size is Large and designed for 21" dog neck circumference.