Chipset: Bluestrum  ANC Depth: 20dB ± 2   Chipset: Bluestrum + AMS  Bluetooth version: 5.0V  Transmission distance: ~10m  Speaker drive: 40mm  Impedance: 32ohm  Frequency: 20-20kHz  Speaker Sensitivity: 105 ± 3db  Microphone sensitivity: -40db ± 3  Battery capacity: 400mAh  Working voltage: 3.7V  NC working time: 40h  Bluetooth working time: 15-20 hours  Charging time: 1.5 -2 hours  MOQ per customized color 2000pcs  with 30cm black Micro-USB cable