One of my friends is offering to sell me a distortion pedal for around 20$ because he can't use it, and I was wondering whether it'd be good or not. I know that this is pretty cheap for a fully working distortion pedal. However, I don't even know fully what it does or even how to use it. Could you tell me what its used for and how its used? And whether it'd be worth the 20$ or not? Thanks!