A Burley Ballz Thru Axle is required for any bike with a 12mm rear thru axle to use the Coho XC (stock thru axles are not able to accommodate any sort of axle mounted hitch system). The Burley Ballz Thru Axle is not compatible with all carbon fiber bike frames (consult manual). - Official Burley Ballz adapter for bikes with 12mm rear thru axles - Includes both the thru axle and Ballz hitch mounts - Quick and easy installation - Specially designed for use with the Coho XC