3/8", malleable iron beam clamp, -16 threaded openings, fits flanges up to 1" thick, supports threaded rod, threaded brindle rings & electrical boxes, malleable iron with electroplated bright zinc plating, set screw rating 750, static load limit 750 lb, based on a safety factor of 3, load rating based on bottom hole of beam clamp, torque inlb 120.