There are no instructions in the box. Solid brass and a strong spring that will easily hold a 1/16 inch and larger bar. The holder comes with two small metal accessories and there are no instructions as to their purpose. It occurred to me that the copper foil should help with the connection between the holder and the weld Since the hole is much larger than the weld wire, I made an alloy insert out of a 9/16" diameter aluminum rod. I used it 8, Drilled 5mm to match the electrode set screw and then threaded from the set screw hole into the insert. Wrapped in copper foil the fit was perfect. I drilled another hole down the center of the insert for the copper filler wire. A set screw then threads through the Brass handle into the aluminum insert and clamps both cables and the plastic handle securely and tightly, but the screw wasn't long enough to tighten it, so I flipped the part over and used it as a sort of spring that keeps some tension on the plastic handle when the set screw opposes it I tightened it just enough to secure the plastic handle. Over tightening may eventually result in some S cause damage. A short piece of closed-cell foam insulation inside the plastic handle and a piece of rubber tubing over the welding wire served as strain relief. Now that everything is finished, I am very satisfied. The instructions will definitely help!