Weight Pulling Sledding Dog Harness X-back Style Black Medium, 19.5" Neck Circumference Light weight harness made of quality durable extremely durable webbing resistant to icing and moisture. Extended foam-like double wide chest plate padding. X-back style for racing or training in any season, made to last. Available in 6 sizes - Small, Medium, Large, XLarge, XLarge, and EXXLarge. This Harness size is Medium and designed for 19.5" dog neck circumference.