Waterproof Design: The Marine Stereo Receiver has been IPX6 rated. One Pair (Total of 2 PCS) 4 speakers have been outfitted with the latest weatherproofing techniques. Bluetooth: Built-in Bluetooth technology allows you to instantly play music via your smart devices– quickly and easily! (like iPhone, android, smartphones, iPad etc). This stereo has no CD player, but has the ability to stream your audio wirelessly. Installation Dimensions: The style of this speaker pair in white makes them easy to install with 4 inch standard size. RECEIVER SPECS – Dimensions Mounting Hole 3.1″ and Dimension Mounting Depth 1.6″. SPEAKER SPECS – The outside facial Diameter is 4.88 with Mounting Hole Diameter: 3.8, and Mounting Depth:1.37. All our products are brand new and sealed. We take our reputation seriously.