Being able to mount your iPhone on your bike is great. But combining an iPhone mount with an eco-friendly silicone amplifier is even greater. This is what the Horn Bike iPhone Mount ($30) is doing for you. This device features an adjustable strap that fits all bicycles and can be set in almost any angle. Your iPhone slides into the silicone sleeve while a horn speaker channels and amplifies the sound in your direction, without the need for any supplementary electricity. The horn is made of eco-friendly, dirt-resistent silicon that can easily be cleaned with water.