This is a quality marine grade stainless steel (AISI 316) chain specifically cut for anchor chain. The link size is 1/4" or 6mm equivalent. Included are two oversized marine grade stainless steel (AISI 316) anchor shackles. Each shackle is 5/16". The total length of chain is 4' measured before the shackles are added. The chain links are made in the European specification style of 6mm (for the chain link size) and 5/16" (for the shackle size). The Imperial equivalent is generally considered to be 1/4" or 15/64" for the chain link size. 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.