Only sold in Japan, this Yamaha motorcycle audio system has speed-controlled volume control and is 100 percent waterproof. Enjoy music anytime on your Harley without helmet speakers or earbuds. You'll definitely be the only kid on the block with this toy and maybe the only one in America!

It attaches to metal tanks like a tank bag. It's powered by the motorcycle's electric system with a quick disconnect harness and uses a wheel sensor to control the volume according to speed. Plug the system's audio cable into your smartphone or MP3 player and you're good to go. Originally cost about $400. Like new condition, electrical harness kit is still unopened. Asking $120 plus shipping via EMS express with tracking.

Here is Yamaha's webpage for it with lots of info, use Google translation.

https://www.ysgear.co.jp/news/2006/0005/