The Problem Solvers Through-Axle adapters make it possible to easily fit front and rear wheels with through axles into truing stands for wheel truing and repair. These adapters fit into the common through-axle sizes and have o-rings so that they fit nicely and stay put as you work on the wheel and take it in and out of the stand. They're made of CNC-machined 6061 aluminum for quality and durability. - Front compatible with 9/15/20mm hubs - Rear: compatible with 10/12mm hubs