This is for twenty (20) quality marine grade stainless steel (AISI 316) 5/16" UNC lifting eye nut. Each bolt is stamped 316 and 5/16" (for the size). The bolts are manufactured in the US style of 5/16" UNC. 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.