This is a 1656-20BH "Chicago" Grip with hot wire latch. The Chicago style grip was a Klein innovation that improved upon earlier designs of wire pulling tools. This particular grip was manufactured in our Skokie, Illinois factory about 1956 and spent its working life pulling aluminum conductor steel-reinforced (ACSR) high-strength stranded conductor cables typically used in overhead power lines. #KleinTools #ToolAddict #VintageTools