Yes, there's a size guide to help you choose the right Aspen Collar. The collar typically comes in different sizes to accommodate various neck circumferences. Before purchasing, measure around the middle of your neck with a flexible tape measure. Match your measurement with the sizing chart provided by Aspen to ensure a proper fit. The correct size ensures optimal support and comfort. AdultShoulder to ChinNeck CircumferenceShortless than 5/8\\"13\\" - 21\\"Regular5/8\\" to 1-1/4\\"13\\" - 21\\"Tall1-1/4\\" to 1-7/8\\"13\\" - 21\\"Extra Tallmore than 1-7/8\\"13\\" - 21\\" PediatricAge in YearsNeck CircumferenceTot1 - 38-1/2\\" to 13\\"Child Short2 - 511\\" to 14-1/2\\"Child Regular3 - 611\\" to 16-1/2\\"