Copper Bare Wire
Bare Copper Wire available in variouse diameters. The thickness of a wire is often given as a Standard Wire Gauge, or SWG.
Various SWG bare wire is often used in electricity experiments to show the effect of the diameter of the wire on the resistance in the circuit.
The most basic explanation on why wire gauge matters is because the thinner a wire is (higher gauge) the more resistance there will be to the flow of current. More resistance means more energy loss, which means weaker/less reliable detections.