This is for four (4) quality marine grade stainless steel (AISI 316) spring hook oblong no eyelet 5/16". Each spring hook is stamped 316. The Metric equivalent is generally considered to be 8mm. 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. Breaking Load Limit = 1118lbs.