This is for four (4) quality marine grade stainless steel (AISI 316) 5/16" UNC lifting eye bolts. Each bolt is stamped 316 and 5/16") and laser etched with the makers mark. The eye bolts are marked with 5/16" which refers to the thread size. 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.