The most important thing is to keep the evidence of the transaction.
But you should also fully understand the goods before trading. The torsion plate may have a bearing limit.
Moreover, the materials to be manufactured should be asked first.
Some materials are entangled with many impurities, which can be seen by the camera.
It can be seen that the workmanship is rough.
Rough surface is basically not a good product. And should know the quality of the axis and cushion in advance.
And keep the chat record.
So that it can be used as evidence of credibility in the future.