Chicago Class F forged steel turnbuckles feature a heat-treated hook on one end with a closed eye on the other. Hook & eye turnbuckles work well when one end of your turnbuckle will have a fixed attachment (for the closed eye) and one end needs to be open to slip over an attachment point (the hook end). Because of the hook fitting, the whole turnbuckle has a downrated Working Load Limit--you always rate your rigging to the weakest link. They meet the performance requirements of ASTM Specification F1145-92, Type 1, Grade 1 (supersedes FF-T-791B). They are hot galvanized and offer a 5:1 safety factor.