Galvanized steel Crosby / McKissick snatch block or roller hook. This is a heavy block with the faded remains of the McKissick label. It's in nice condition, except for the finger on the hook, which is bent up.
It's about 15" long over the hook and about 4 1/2" across the pulley. We're not sure of the weight rating. The body is is marked "8" (right side in the 5th photo), so maybe 8000 pounds? or 8 tons? Use your judgment.