A级=pu皮，人造革，亮金色五金 AA级=真皮，二层皮，半钢五金 AAA级=头层皮，原厂皮，全钢五金. Grade A = PU leather, artificial leather, bright gold hardware AA grade = leather, two-layer leather, semi-steel hardware AAA grade = first layer leather, original leather, all-steel hardware