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