The Groove Tubes Fat Finger is a unique guitar piece that aims to add sustain to your electric guitar.  It attaches to the head stock of your guitar and is supposed to allow your guitar to sustain a bit longer, and I do believe that it does this.  Let me start of by saying however, that I don't believe this is necessary for anyone's guitar, but at times can be a cool gadget to have around.  It was easy to attach to head of the guitar and I didn't find that it feel off easily or anything like that as it stayed in place pretty well.  I can't say the Fat Finger will give you infinite sustain or anything close to it, it will loosen your strings a tiny bit and will make it a bit easier to sustain your strings.  However, if I'm looking for real sustain I will usually use a compressor, as this doesn't have the capability for sustain like that.  It isn't the type of thing that I would use on every song, only on some here and there where I feel I might want a bit more sustain.  The Groove Tubes Fat Finger is cool with effects like reverb and delay, but like I said earlier, it definitley isn't a necessary piece of equipment.  The good news is that it is a very low priced piece of equipment, which is the main reason that I tried it out to see if it could help at times even a little bit.  This is definitely an intersteing concept, as I don't think that I had seen anything like it before I got this one.  If you're intrigued by this at all, I'd recommend just checking it out and seeing if it is something that you might want to use.