Wireless 2.4 GHz It is microphone set couple automatically,easy to operate,both trasmitter and receiver work on rechargeable lithium battery. up to four identical systems can work together , up to 6 hours using time . suitable for many different, such as presentations, educational events and singing performances. Headset With Separate Trasmitter It can be used as a computer michrophone and for video sound recordings. SPECIFICATION Frequency range:2.4 GHZ Frequency response:20 Hz - 20 KHz (+- 3 dB) Output impedance:2200 ohms Pairing method:Automatic Microphone type:Condenser Microphone directivity:Unidirectional Microphone dimensions:6 x 2.7 mm (0.2 x 0.1") Microphone sensitivity:- 45 dB (+- 2dB) Signal to noise ration:> 63 dB Power supply:Rechargeable lithium battery Power consumption:< 70 mA at 0 dBm Operating voltage:2.0 - 10 V DC Operational distance:25 metres (82 feet) Operational time:Up to 6 hours Included:6.35 mm (1/4") audio adapter plug and double charger cord الحالة جديد