Feature:1. Clear Sound: Reliable RF connection coverage up to 100m/328.1ft. Up to 90 dB signal to noise ratio provides clear, complete sound at any volume.2. Simple and Durable: There are no complicated menus, just simple buttons for volume and mix controls. Transmitter and receiver are all metal cases, strong and durable.3. Unlimited Receving Numbers: The number of S3 receivers available at the same frequency is unlimited. Stable performance and high sensitivity.4. Compact Size and Modes: The compact Fanny pack receiver is easy to strap onto a belt or guitar belt. Three reception modes: mix, stereo, mono.5. Maximium 8 Systems: Up to eight wireless listening systems can be used simultaneously in each frequency band.Specification:Item Type: Wireless Earphone Monitor SystemMaterial: Iron ShellFrequency Range: 830-866mhzEarphone Output Interface :3.5mm Stereo SocketTransmitter Power: DC12v/300mAReceiver Operating Time: More Than 12 HoursReceiver Batteries: 2 x AA Batteries (Not Included)Operating Range: 100m(Open Environment Without Shelter)RF Transmission Power: <10nWDynamic Range: 90dbHarmonic Distortion: <1%(1KHz,20KHz Frequency Offset)Frequency Response: 40Hz-18KHzHeadset Output Power: 65m(32 Ohms)Voltage: 110-240V.Package List:1 x S3 Transmitter 1 x S3 Receiver1 x Power Adapter1 x Description 1 x Antenna 2 Pairs x Ear Cap 1 x Headset 1 x Battery Compartment