This is for one (1) quality marine grade stainless steel (AISI 316) anchor chain lock. This chain lock is suitable for 6-8mm (or 1/4" - 5/16") chain. The chain lock can be used to remove a load from an anchor windlass or to transfer a load to a cleat. 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.