Features: 4MM is smaller than small, so small that you forget its existence. The brand new sleep Bluetooth earphones are comfortable to wear without falling off, smaller and more invisible, with a small body shape that can be hidden and a good sound that cannot be hidden Made with meticulous craftsmanship and ergonomic design, it is suitable for 99% ear shape and will not cause swelling or pain when worn in small ears. Half in ear design that fits perfectly with the ear, making it compact and stable Can't shake it off, truly invisible and comfortable to wear. BT version: V5.3 Earphone diameter: 4mm Sensitivity: 92 soil 3dB Impact range: 20-20kHz Earphone capacity: 35mAh Charging compartment capacity: 1500mAh BT protocol: A2D/AVCRP/HFP/HID Packaging includes 1 * Earphones 1*usb cable 1 * Instructions