Grab a cold one, put your feet up and enjoy the water with the UM1A source unit with app control technology. This new stereo features the Polk Ultramarine app, providing you with the ultimate wireless remote control for a Polk Ultramarine stereo system. Now available for both Android and Apple iOS smart device users, this free downloadable app allows boaters to control all of the primary functions of the Polk Ultramarine stereo system from one convenient, easy-to-use mobile application. It's the perfect controller made to fit the boating lifestyle!