Stable Signal Bluetooth V4.0 tech providing stable Bluetooth signal, ensure smooth sound transmission. Adjustable Design Provides maximum portability & convenient storage and very convenient to fit with your head. Comfort Lightweight and comfortable, with soft-skin ear pads, you can wear these for hours without any irritation. Decent Sound 40mm drivers deliver rich bass and crystal clear treble, 20Hz-20KHz frequency response for fuller listening enjoyment and have a clear phone talk due to the sensitive microphone. Line in Mode Insert the 3.5mm audio jack, you can use the Bluetooth headset as a normal headset. Specification Bluetooth Version: V4.0. Bluetooth Profiles: HSP, HFP, A2DP, AVRCP. Work Range: 10Meters. Lithium Battery Capacity: 300mAh. Frequency Response: 20Hz-20KHz. Sensitivity: 105dB (AT 1KHZ 3dB). Impedance: 32 . What's in the Box: 1 x G-Cord Headphones. 1 x Micro USB charger. 1 x User Manual. 1 x Audio line.