Brand Suckoo 4 Channel 6.35mm TRS or 3.5mm Audio Mixer Headphone Amplifier 4 In 1 Out 2 In 1 Out for 4 Port Cell Phone Computer MP3 Musical Instrument Guitar Mixer Controller with External 1 Channel Audio Headphones Stereo Sound Speakers. This 2 in 1 audio mixer headphone amplifier is very practical with 6.35mm TRS or 3.5mm audio jacks for connecting 4 channels at the same time for mixing or one of the audio computer inputs alone, external 1 channel audio headphone speaker device, 4 channel audio source with individual control of volume level and gain function. Input 4 channel 6.35 mm TRS or 3.5 mm instruments, guitars, microphones, cell phones, computers, MP3.External 1 6.35 mm or 3.5 mm audio headphones, speakers Speakers.Color: Black, Product size: 10.5x5.7x3.2 cm. Accessories: 1 x this product + 5PCS 6.35 male to 3.5 female adapter + 1 free DC adapter. This mixer headphone amplifier input 4 way volume adjustable gain function, you can adjust the volume level and gain of each input channel as needed to meet the needs of different users. This is useful for scenarios such as music production, recording studios, performances or movie viewing. All in all, this mixer headphone amplifier 4 in 1 out is a full featured, convenient and practical audio device that can help you mix and adjust the volume and gain of audio signals.