[Bluetooth 5.3] Adopting Bluetooth 5.3, the transmission of AIRERSI headset K21 is faster, more efficient and stable. You can move freely with up to a 59 ft (18 m) range. Headset features multipoint technology, enjoy the convenience of having up to two devices connected at once.

[CVC8.0 Dual Mic Noise Cancelling] AIRERSI K21 bluetooth headset features dual mic CVC8.0 and ENC noise cancelling technology, knock out 96% noise and deliver clear voice. Enjoy clear calls.

[Echo Cancelling & Clear Voice] AIRERSI Bluetooth headset K21 adopts Echo Cancelling and Consistent Voice Quality technology for clearer calls. Consistent Voice Quality technology conceals Packet-loss and bit error effectively to ensure consistent voice quality even in situations where bluetooth connectivity may be compromised. Hope you enjoy consistent clear call.

[Comfort-Test Design] Rigorously tested for stability and comfort on a wide range of ear shapes means you’ll feel just as comfortable during your first call as your last call. 3 pieces different sizes ear tips to meet your need. Only 0.04lbs / 20g，sleek and pocket-size, K21 headset is perfect for on-the-go communication.

[Long Battery Life] Equipped with a 150mAh battery, allows you to talk freely throughout the day. With up to 16 -18hours of continuous talking on a 1.5 hours single charge. Equipped with a 800mAh charging box, it can provide 4-5 charges for the headphones,K21 Bluetooth Headset works with iPhone, Androidand and all smart phones.