Our dog collars are fully adjustable. They are made of machine washable cotton fabric with a nylon core except for small collars. Small collars are made of machine washable cotton fabric with an interfacing core. Interfacing is a fabric stabilizer that gives the collar stability and form. Collars feature a nickel plated d-ring, plastic triglide and a plastic side release buckle. Each collar is handmade to order. Please note: Our collars are not approved as tie out collars and are not recommended for excessive pullers. We do offer a variety of buckle sizes. Please refer to chart below: Collar Lengths with available buckle widths. Buckle width indicates the width of the collar. Small 7-10” (Available Buckle Size - 5/8”) Medium 9-14” (Available Buckle Sizes - 3/4” & 1”) Large 13-18” (Available Buckle Sizes - 1” & 1.5”) XLarge 16-23” (Available Buckle Sizes - 1” & 1.5”) Custom sizing is available upon request!