This amazing portable silicone mini speaker amplifies the sound from your iPhone by up to 15 dbs. (feels like 2-3 times as loud) without any batteries. It uses old fashioned horn or megaphone technology. Holds iPhone vertically, horizontally, and has opening reserved for charger. It also works well in hands-free mode. Works only with iPhone 4S, 4G, 3S and 3G phones.