This is for marine grade stainless steel (AISI 316) anchor shackle with square head pin. Each shackle is stamped 316 and laser etched with the manufacturer's mark. The shackles are marked in the US size specification. Not to be used for overhead lifting. AISI 316 stainless is a premium grade of stainless and is considered by many to be best in class. 316 stainless is corrosion resistant and very durable even in the harshest of conditions.