VicTsing Shower Speaker, Wireless Waterproof Speaker with 5W Driver, Suction Cup, Built-in Mic, Hands-Free Speakerphone-Blue. Suction cup x 1. Support A2DP and it's 5W speaker, so give you much better quality stereo experience (Just as the pic show that most of the popular waterpoof speaker just have 3W speaker).
eBay