The DT Swiss Thru Bold Conversion End Caps seamlessly adapt newer DT Swiss wheels to accept older axle standards, so long as you're running a compatible DT Swiss RWS thru-bolt (not included) in either 9 (front) or 10-millimeter (rear) diameters. The 9-millimeter front adapter works with DT Swiss 350/370 hubs on road disc and mountain bike wheels, fitting 9 x 100-millimeter thru-bolts (not included) to a hub/wheel that previously only accepted 15 x 100-millimeter axle spacing. Compatible wheels include the R23, R24, Spline 1700, and Spline 1900 front wheels by DT Swiss. Looking to the 10-millimeter rear adapter, you'll find it fits a 10 x 135-millimeter thru-bolt (not included) to a DT Swiss 180/240/350 11-speed, straight-pull road disc hub that previously only accepted 12 x 142-millimeter axle spacing.