(1) The speaker has two binding posts (two leads). When a single speaker is used, the two pins have no polarity. When multiple speakers are used at the same time, the two pins have polarity.
(2) The speaker has a paper cone, its color is usually black, but also white.
(3) The shapes of speakers include round, square and oval.
(4) There is a magnet on the back of the speaker cone. If you use a metal screwdriver to touch the magnet with an external magnetic speaker, you will feel the presence of magnetism. There is no such feeling in an internal magnetic speaker, but there is a magnet inside the casing.
(5) The speaker is installed on the machine panel or inside the speaker box.
