All the features of the ES-4 plus a built-in amplifier. The advanced ES-4P has volume control, tone control and a switchable attenuator that helps prevent accidental over-driving. It ramps the audio level to a whopping 94 dBA, while improving tone and clarity. It has a 3.5mm plug for audio input, and runs on 12vDC

Most VHF radios provide external audio outputs. These accessory speakers are color and performance matched to make installation a breeze.
Easily installed on any boat by your marine dealer or you can even install it yourself.