Since speaker connections are polarized, the terminals are typically color-coded so that the positive wire connects to the red and the negative to the black terminal.
The terminal consists of a spring-loaded metallic pincher that opens when the lever is pressed, and when released will tightly grip the conductor which has been inserted into it.
This type of terminal is popular because it does not require any special connector to be applied to the end of the wire; instead, the wire is simply stripped of insulation on its end and inserted into the terminal.
DIY projects sometimes reuse speaker terminals for other applications using bare wire leads.
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