Size Small: Neck 12"-16", Width 5/8"Size Medium: Neck 14.5"-20", Width 3/4"Size Large: Neck 18"-26", Width 1"The collar does not stretch itself. Martingale collar is a slip collar **WITHOUT THE BUCKLE**, which is designed for sighthouds but becomes popular with other breeds. Please take the measurements at the head and neck showing in the size chart. Especially for non-sight hounds, PLEASE CHOOSE A COLLAR SIZE THAT IS LARGE ENOUGH TO SLIP OVER THE HEADAbout Blueberry PetThe story of Blueberry Pet is built on the spirit of unique design, elevated craftsmanship, and premium quality. Within a decade, our brand has been well recognized and loved by pet parents and lovers. We have made history by selling award-winning pet collars, everyday walk staples of harnesses, limitless choices of pet apparels, well-curated pet toys and accessories, pets friendly home dcor and matching products for pet owners. We emphasize on elegant simplicity of the details, pay great attention to feasible innovations of mass-produced products and appreciate sense of togetherness from pet community. This sense of togetherness and continuity enables Blueberry Pet to extend the attention to design, materials and honor the bond between humans and animals. We aim to create functional everyday looks, delight pet parents and make furry friends smile.