This is for two (2) quality marine grade stainless steel (AISI 316) linchpin ring catch. The size is 4.4mm or 11/64" nominal. 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.