This is for one (1) quality marine grade stainless steel (AISI 316) eye bolt M12. Each eye bolt comes with the nut and two washers. The eye bolts are made in the metric style of M12. The Imperial equivalent is generally considered to be 1/2", but this thread and nut are metric M12. The length measurement is the length of the (usable) threaded section of the eye bolt (150mm). 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.