applications. Specification: Model number: BX501 Material: ABS ' Metal Color: Grey ' Black Carrier frequency: 2.4GHz Modulation method: GFSK Transmission rate: 2Mbps Transmission power: '10dBm Channels: 16 Channel spacing: 5MHz Working distance: 50 meters / 164 feet(outdoor open area)        Receiver: Input signal effective value: 1Vms Input impedance: 10Kohm Output / input gain: 1:1 Frequency response: 20Hz~20kHz (-3dB) Transmission delay: <3ms Sampling rate: 44.1kHz, 16Bit Dynamic range: 92dB, SNR: 90dB Harmonic Distortion: 1.0% at 1KHz Left and right channel isolation: 80dB Built-in 320mAh li-poly battery in sender box (no built-in battery in receiver box) Power supply: DC 5V, Current consumption: 65mA Operation temperature: -10~60℃ Plug: US, EU(optional) Item size: 7.9 * 6.1 * 1.5cm / 3.1 * 2.4 * 0.6in(L * W * H) Item weight: Approx. 228g / 8oz Package size: 22 * 15.3 * 4cm / 8.7 * 6 * 1.6in(L * W * H) Package weight: 312g / 11oz Package list: 1 * Wireless Audio Music Sender 1 * Wireless Audio Music Receiver 1 * 3.5mm Audio Cable 1 * RCA-to-3.5mm Cable 2 * USB Power Adapter(EU Plug) 2 * USB Power Cable 1 * User Manual Note: This product's wireless transmission frequency is 2.4GHz, which meets European R & TTE Directive 1999/5/EC's requirements, its radiation will do no harm to human body(far less than phone's radiation).           Wireless transmission will generate electromagnetic signals, pls cautiously use it when in operation of cardiac pacemaker or other body auxiliary equipments.           Please confirm the plug type when you make the order, if you are not sure which plug you want, you could contact with us, we'll help you to choose, thank you!