and it needs to have the above two characteristics The passage latch lock body must be made of stainless steel, and the lower price of the product is stainless steel 201. This kind of product usually rusts due to the environment and usage after one to two years, and the fire resistance is not very good. Therefore, developers who have requirements and heavy quality will usually choose the passage latch lock body made of stainless steel 304, because it is not only fireproof, but also not easy to rust, and the quality is relatively good.