If you use your Apple Watch for exercise, these Vi Bluetooth headphones are a must-have—Apple HealthKit-compatible—accessory. The personal trainer works with Apple HealthKit to create a customized workout. It learns how you run and monitors stats like your heart rate, motion, and elevation. The Harman Kardon headphones have waterproof earbuds that actually stay in your ears, plus a battery life that lasts all day. They also, of course, let you answer phone calls or listen to music from your watch or smartphone.