That’s a Wire Rope Clip also called a U-bolt clamp / Crosby clip / "U-clamp"
Brand: TOYO stamped on it
What it’s used for:
To make loops/eyes in wire rope / steel cable and to join two ends of wire rope together.
It’s basically for "terminating" or "splicing" steel cables.
How it works:
1. You bend the wire rope back to form a loop
2. Put this U-clamp over the 2 strands
3. Tighten the 2 nuts with your wrench/spanner
4. The U-bolt squeezes the "dead end" to the "live end" so it won’t slip