We recommend an external CB speaker for every radio. Every CB radio has a built in speaker. On most radios, this speaker is on the bottom of the radio facing down. This makes it difficult to hear since a lot of the sound is lost in your carpet or dash. By installing an external speaker, you are able to face it directly at yourself. This will let you keep the volume (and background noise level) down on the radio. The benefit is magnified further if you are able to mount the speaker closer to your head.
All of our speakers include a length of wire terminated in the 5mm plug our radios use for connecting an external speaker. The main differences in the speakers are size and power capability. Some of the speakers also include features like noise canceling, amplification, or talkback.