8. Bolts and nuts should be able to fit. When the bolts and nuts are matched, the nuts should be screwed to the bottom, and there is no peeling off of the bolt threads.
8. Bolts and nuts should be adaptable. When the bolt and nut are compatible, the nut should be tightened to the end and there should be no peeling of the coating on the bolt threads.
8. Bolts and nuts should be adaptable. When the bolt and nut are matched, the nut should be screwed to the end, and the bolt thread has no phenomenon of falling off a piece of coating.