Pack a lot of power into a small space with Soundstream ST4.1000DB 4-Channel marine amplifier. Its efficient Class-D design combines stable performance, low power draw, and excellent sound quality into a small Footprint that's a great match for boats, motorcycles, ATVs, or any application where space is tight. Built-in Bluetooth lets you play your favorite music directly from smartphones and other mobile devices Without the need for a receiver or the hassle of cables and plugs. Whether you're out on the water or up on a mountain, that's a big benefit.