Here is a Bluetooth speaker made with golfers in mind. The Precision Pro Ace Bluetooth GPS Golf Cart Speaker comes with a magnetic mount. It not only plays your music but also can tell you GPS distance to front/center/back of the green. The Ace Speaker lasts up to 24 hours on a single charge.
With the companion app, you can learn club distances and see detailed on-course information. It has info on over 37000 courses. The device has a LCD display to show GPS distances.