Characteristics:1. Touch the Bluetooth button with your finger to control media playback without touching your phone.2. Can control media play, pause and track forward and backward, and also can adjust cell phone ringtone volume and media play volume. Even if you put your phone in your pocket or wallet, you can operate it from an effective distance of 12 meters.3. Good compatibility:For iOS devices, support Bluetooth 3.0 or aboveFor Android device, support Bluetooth 4.0 or above4. Compact design with a diameter of 35mm.Specifications:Material: ABS + aluminum alloyBattery: CR2016 button cellSize: 35mm / 1.38 "in diameterInstructions:1. Make sure your phone's Bluetooth is on.2. Press and hold the pairing button until the light turns blue and flashes.3. Check if the “Bluetooth media button” already exists in the device list.4. Select "Bluetooth multimedia button" and wait for the context menu.5. Click on the "pair" button in the context menu.Notes:1. There might be slight size deviations due to manual measurement, different measuring methods and tools.2. The picture may not reflect the actual color of the item due to different photography light, angle and display monitor.