This is for four (4) quality marine grade stainless steel (AISI 316) spring hook with eyelet 1/4". Each spring hook is stamped 316. The Metric equivalent is generally considered to be 6mm. 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 = 598lbs