Features: 5-band EQ preamplifier: adopt 5PCS JRC4558 op amp, each one is responsible for one frequency band and process the audio signal independently. 5-band separate control knob, to control and set the freqency range as you like. Bypass design suits more use: with bypass button to turn off EQ preamplification, the audio signal will output from IN to OUT directly without any processing, convenient to enjoy sound. Attractive looking and powerful design: case and PCB panel, knurled knob, all I/O interfaces are gold-plated to the tight connection and transmission of the audio signal and minimizes the loss of the signal. Mini size and powered by DC 5V: compact design easy to carry, convenient to use in most scenarios, no need to bring a separate power supply, very suitable for of most users. Paramters: Audio input: stereo RCA / 3.5mm AUX Audio output: stereo RCA / 3.5mm AUX Input impedance: 50K Output impedance: 47 Frequency response: 5Hz-154kHz : 0.003%@1KHz EQ Bands: 100Hz, 400Hz, 800Hz, 4KHz, 10KHz Bypass function: support Working voltage: DC 5V (500mA) Power interface: USB (type-C) Material: Plastic + metal colour: As shown Package Contents: 1 x EQ5 Preamp 1 x USB Cable (type-C) 4 x mats Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.