High Performance Bluetooth Headphones with Active Noise Cancelling Technology. Sophisticated Active Noise Cancelling Technology for significant reduction of ambient noise. Bluetooth 4.1, Active Noise Cancelling Technology, Alternatively wireless or wired sound, Detachable audio cable included, High quality metallic design, Fully foldable, Super-soft & durable ear cushions, 8 hrs operation time, Built-in 250mA lithium battery, USB charge cable included, Incl. Hard case, Color: Dark Bronze. Driver: Ø 40 mm, Frequency range: 20-20.000 Hz, Sensitivity: 97 dB, Impedance: 32 Ohm, Max Power Input: 30 mW, Operation distance: 10 m, Frequency range Microphone: 20 Hz—16 kHz, Sensitivity Microphone: 42 dB.