This is for two (2) quality marine grade stainless steel (AISI 316) turnbuckles (or open body) eye and eye with locknuts. Each turnbuckle is stamped both 4 the metric size and 316 the grade. This is an M4 metric turnbuckle. The imperial equivalent is generally considered to be 5/32". 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.