This is a CNC machined aluminum adapter for BMW motorcycle rear wheels so you can mount your wheel and tire on your balancing stand. It is bored for a 1/2" (.500") shaft. It will not work with a 12 mm (.472") shaft as normally comes on a Chinese balancer stand so be sure to measure your shaft accurately. If you need a 1/2" shaft for your balancer I have listed them on eBay in various lengths. Please search for 296131158642.