This Sentry speaker system can be expanded up to 6 speakers plus can take on a wireless headphone to the system. You can plug any audio device that has a 3.5 mm headset port directly into the unit for easy plug and play. The transmitter lets you charge your iPod or MP3 player through the built in USB Port. Since the system is water resistant, it is can be around the pool, but never in it! You can hook in your CD player, iPod, mp3 player, receiver, cable box, etc. Sentry Wireless Indoor/Outdoor Speakers and Transmitter is available at Amazon.com for $99.99

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