In special occasions, bike racks need an adapter to fit the trending fatty axle. RockyMounts DriveShaft is a 15mm/20mm thru axle adapter that can handle both loads and the only one on the market to securely lock up your bike. It fits standard fork mounts from RockyMounts, Yakima, and Thule. Its wide mouth opening creates easy loading, holds tight with adjustable cam lever, and comes with snap in nylon shims to prevent the axle from being unscrewed and gives the ability to switch from 15mm to 20mm thru axles, just like that. Comes with RockyMounts locks and keys.