One 1/4" instrument input and one mic input. Stereo/mono switch. Line or Instrment switch.
For a recording interface, this is a simple as it gets. You can plug your guitar or other instrument directly into the 1/4" jack or go through a POD or similar first and then into the FastTrack, and then into your computer. Or you can plug in a mic.
The Mic input knob controls the signal level going to your recorder. The Mix knob adjusts the live signal as it relates to the backing track. Turn it one way, you get more backing track, turn it the other, you get more you. The Output knob controls the output level.
It's portable enough to take just about anywhere.
It's very tough control the signal input level if you're micing an amp that is running really loud. The simplicity of the knobs works against you here. If you're running your amp loud (power amp distortion loud), you need to turn down the Mic input or your signal is going to both peak the signal light on the FastTrack, and peg your meters on your channel strip. Even at the Mic input's lowest possible setting, the signal is still too hot. I have a good mic pre between the mic and the FastTrack, so I can dial back the levels with that mic pre, but if you don't have another piece of hardware or software between the FastTrack and the mic, you're not going to be able to control a hot signal such as that coming off a mic'd cab when running the amp anything near full out.
This is an inexpensive audio interface that is ok for some down and dirty "Fast Tracking." It will work fine for recording things like bass, or guitars direct, or with a POD/Preamp in front of the AI. It is no where near ideal for pro-quality recording of guitars or vocals.