Binding post

A binding post is a connector commonly used on electronic test equipment to terminate (attach) a single wire or test lead. They are also found on loudspeakers and audio amplifiers as well as other electrical equipment.

A binding post contains a central threaded metal rod and a cap that screws down on that rod. The cap is commonly insulated with plastic and color-coded: red commonly means an active or positive terminal; black indicates an inactive (reference or return) or negative terminal; and green indicates an earth (ground) terminal.