JOYO I-PLUG Electric Guitar Amplifier Portable Mini Headphone Amplifier 1. Instrument jack: 6.35mm single-core socket 2. Maximum input level: -10dB 3. Input impedance: 1M ohm 4. Headphone jack: 3.5mm 5. Link jack: 3.5mm 4-pin socket 6. Link input impedance: 100K 7. Link output impedance: 10K 8. Power: Two 1.5V AAA batteries 9. Built-in distortion effect. 10. Designed with 3 adjusters: volume, tone, gain. 11. The back is designed with a clip, which is easy to fix on the belt, pocket or anywhere else. 12. It allows you to practice your instrument without disturbing others or being distracted. 13. When connected to smart devices, such as iPhone ipad ipod, IOS devices like AndroidWindows phones, and your favorite apps from the app store. You can choose any effect you want to play, or you can easily use this system to record your practice or performance. 14. The I-Plug has a mono jack (6.35mm), a 4-pin 3.5 jack for Apple devices (may need an adapter to reverse polarity to connect to other Android or Windows smartphones), a 3.5mm stereo headphone output. It is powered by a 3v battery; the control panel has a drive knob, tone knob and volume knob.