Overview The advanced chip guarantees exceptional performance by delivering consistent and lossless audio streaming, guarantee the stability of the connection signal within 20 meters between the earphone and phone. TF Card MP3 Music Mode Clear Sound, HIFI Bass 10mm large strong magnet speaker makes good music CVC Audio Technology could cancel the background noise when calling. All-day Listening(500mAh battery) Enjoy about 40 hours of music time after a full charge About 300 hours standby time Neckband lightweight design with soft material Perfect Fit, Never Fall Out Lightweight and ergonomic design fit in your ears securely and comfortably. Never falling out even when you're running. Simple Button Control Volume control, songs change, play and pause, answer and reject calls with the just press on the buttons on the right earphone, no need to operate on the phone. Specifications Transmission range: 10 meters Function: Battery display, call function, music support, multi-point connection Bluetooth protocol: 5.0 Channel: Stereo Usage: Hanging ear type Single or dual-ear: Bilateral stereo Color: Black red, black silver, obsidian, black green K31 is equipped with a 500 mAh high-capacity battery, which can continuously listen to songs About 40 hours, let you enjoy sports. 5.0 ear-mounted non-ear wireless sports waterproof, a card can be inserted Package Content 1x Bluetooth Earphone 1x Manual 1x Charging cable 2x Spare earplug