<ul><li>Easy to use: A multi-function button can answer, reject, hang up, redial, mute a call, or double-click the multi-function button during a call to mute Comfortable to wear: 180&deg; rotating earplugs, three different sizes of ear cups for comfortable left and right ears, light and comfortable, can be worn for several hours at a time Bluetooth 5.0: With the latest Bluetooth 5.0 technology, pairing and connection are faster and more stable. Built-in advanced boom microphone and dynamic speaker for clear, realistic sound. Noise-cancelling microphone for various environments Hands-free: Long press the call button to activate (Siri) voice assistant for hands-free, more convenient to use in business office According to manual measurements, the difference is 2-3%. Please check the size chart carefully before purchasing the product. Please note that due to the effects of light and screen, slight chromatic aberration should be acceptable.</li></ul>