IN EAR MONITOR SYSTEM: This ear monitor can amplify sound and has two top knobs. The VOLUME knob adjusts the total output of the earphone, and the BALANCE knob adjusts the mixing balance of stereo sources connected to two input terminals, or adjusts the balance between left and right channels or mono sources connected to input terminals 1/L and 2/R. INTERFACE INTRODUCTION: The design features XLR and TRS input connection, with locking function and 3.5 mm headphone output, providing wide volume range, clear audio quality and low distortion. MONO/STEREO MODE: The headphone amplifier offers a mono/stereo switch function, allowing you to flexibly choose between various options to meet different needs in different situations. EASY ACCESS TO BATTERIES: The headphone amp features an innovative, tool-free belt clip design that allows you to access the batteries at any time. ULTRA-COMPACT: The in ear amplifier has an extremely compact body and is made entirely of metal. Color:White Material:Metal Package Contents: 1 * mixer