Spud Wrench 1/2-Inch Bolt for Heavy NutSpud Wrench 1 2 Inch Bolt for Heavy Nut Forged from select alloy steel, the Klein Tools 1 2 Inch Erection Wrench is designed to withstand high leverage and heavy loads. It's designed for use with 1 2 Inch bolts and U. S. heavy nut types. The extra duty head area gives maximum strength and durability. Plus, the continuous taper of the handle makes it easy to line up bolt holes.