Rear wheel bearing extractor tool for use on most modern trials bike with a 17mm rear axle.
The tool has a 20mm diameter spigot that slides inside the 6004 wheel bearing and presses against the internal aluminium bearing spacer, the tool also has a small 17mm spigot that holds this spacer central while you press the bearing out of the other side of the wheel. The tool can then be removed and put in from the other side of the wheel to remove the other bearing.