2 Channel Stereo Mixer, 2 in 2 Out Low Noise Independent Volume Control 3.5mm Small Sound Mixer for Headphone DC 5‑24V music_update_2022 so they are mostly used

so they are mostly used for maintaining the rechargeable battery and recharging your phone for a short call in emergent situations

making it compatible with most devices such as laptops

do not use these products

TRS/TS cable is not included in package

2 Channel Stereo Mixer, 2 in 2 Out Low Noise Independent Volume Control 3.5mm Small Sound Mixer for Headphone DC 5‑24V music_update_2022 so they are mostly used2 Channel Stereo Mixer, 2 in 2 Out Low Noise Independent Volume Control 3. 5mm Small Sound Mixer for Headphone DC 524V Product Features STEREO 2 IN 2 OUT: 2 simultaneous sound inputs and outputs can be connected. Separate volume adjustment knobs for listening to music and mixing multiple sound sources (including sound) through headphone and speaker outputs. 6db amplification gain, the first stage op amp is the for NJM4580, the second stage driver is