PAWZ Road Pet Clothes Cold Weather Dog Vest for All Kinds of Dogs 4L:Back Length 21.7"/55cm Chest Girth 27"/69cm Water Resistant Outer layer/ Soft and Warm Inner Layer The O-Ring on The Back is Sturdy Enough for SML, But Not Strong Enough for 6L7L Dogs.So Plz Double Think If You Concern It Too Much Zipper Closure Makes It Easier to Wear and Take Off Size Chart been Mix up by other sellers. Plz Choose Seller Sweet Pet For Standar Size Guarantee