The BOYA BY-WM5 wireless microphone is compact, high performance, lightweight, and compatible with DSLR cameras, camcorders, audio recorder etc. It features experience more freedom of movement while recording, excellent sound quality, great portability, easy setup, two way communication system, and approximate 50m(164 ft.) operation range. It consists of a transmitter, receiver, two piece of earphone( one is with speaker), an audio signal cable, a lavalier/lapel microphone. Specifications: RF Modulation:GFSK (Gauss Frequency Shift Keying) Frequency Band: 2.4GHz (2405-2478MHz) Frequency Response: 35Hz - 14KHz¡À3dB Signal/Noise: 76dB or more Distortion: 0.1% or less (32ω, 1KHz, 65mW output) RF Output Level: 5mW Reception Sensitivity: -85dB +/-3dB / 0dB=1V/Pa, 1kHz Audio Input Connection: 3.5mm mini jack Operation Range: 50m (164ft.) Power Requirements: 3.0V DC (Two LR03/AAA size batteries) Consumption Power of Transmitter: 3.3 V / 110 mA Consumption Power of Receiver: 3.3 V / 100 mA Battery Life: Transmitter approx. 3.5hrs / Receiver approx. 4hrs Dimensions of Transmitter: 2.36 x 3.3 x 1.1 in / 60 x 86 x 28 mm Dimensions of Receiver: 2.36 x 3.3 x 1.61 in / 60 x 86 x 41 mm Weight of Transmitter: 4.37 oz / 136 g (without battery) Weight of Receiver: 4.89 oz / 152 g (without battery)