SX-991 Bluetooth headset is designed to direct sound straight into your ears with noise isolating ear gels for deep bass and rich audio. Built-in high sensitivity microphone and noise canceling technology (not active noise cancellation), ensure crystal high quality sound no mater you are calling or listening to music. The portable designed headphone built with large capacity battery, provides up to 16 hours of continuous music time and 300 hours of standby with a single charge. Latest Bluetooth 4.1chip provides fast, stable and low-power connection. These headphones are compatible with most smart phones, iPhone, Android devices and other Bluetooth Enabled Devices. Around-the-Neck wearing design with perfect Body-Contoured fit. Made of environmental ABS+PC material, light and soft to wear comfortably, perfect for long time wearing no matter in outdoor activities or in office. Foldable design enables you to take it anywhere in your pocket or in your bag. Retractable Earbuds- a unique design for cable management, no more tangled wire obsession. This Bluetooth headphones vibrate automatically when there is a phone call, never miss any phone call even in a noisy environment. Featured with CVC Version 6.0 noise cancellation technology, ensure crystal sound for music and clear voice for calls. Premium soft silicone gel surface is sweat-proof for stable wearing. Ideal for Gym, running, hiking and other outdoor activities.