Combining all that you need to run, the run pack features the Wahoo Key and the Wahoo Fitness soft heart rate belt in a convenient bundle. What is Wahoo Fitness? Wahoo Fitness products wirelessly connects your smartphone to fitness sensors. With Wahoo Fitness, your phone, the best fitness Apps and real-time activity stats are all in the palm of your hand - or on your arm, or mounted on your bike. smart phone. smarter athlete. Wahoo Armband for iPhone This is the best iPhone armband you can buy! Weather and sweat-proof, the Wahoo Armband was designed for the iPhone 3G, 3GS, 4 and iPhone 4S with the Wahoo Key attached. Unique design provides unmatched comfort, convenience and protection while you run, workout or listen on the go. Features Weather and Sweat-Proof unique design and Neoprene and PVC construction Soft and Comfortable Thick neoprene band cinches snugly to your arm to minimize bouncing and chaffing issues Headphone port Side headphone port keeps sweat/rain from gettin in your iPhone (headphones not included) Smart design Features a velcro holder for your excess headphone cord Size Fits up to 14 inch arm (355 mm) Fits iPhone and iPod Touch Designed to hold iPhone 3, 3GS, 4, 4S, iPod Touch 3, 4 with the Wahoo Key attached Will not fit Wahoo Bike Case