Country Brook Design | Thanksgiving Feast Ribbon Martingale Collar - Medium Collar Fits 15in-21in neck- There are no standard sizes for dog collars. Please be sure to measure your dogs neck for correct size. Measure around your dogs neck (with string or tape measure) snugly where you want the collar to lay. If you have any questions or problems with sizes please give us a call before ordering. Made in the U.S.A. Made using top quality hardware Traditional martingale collar has no buckle for superior strength.