Please read the profile before purchasing. Important requests regarding transactions are stated. Your understanding and agreement with all of them are key to a smooth transaction, so we appreciate your cooperation. Although the official name is unknown, this is a double-ended bolt snap hook clip (set of 4, new). The material is molybdenum-added "316 stainless steel," a high-grade material that is particularly resistant to rust and durable among stainless steels. I myself have used the same product in the ocean for many years, and I have never had any rust with simple water washing maintenance. I have bulk inventory purchased from the manufacturer, and I am selling it at a lower price than retail to organize some equipment.