The Johnson Harmonica Holder is a simple contraption for holding a harmonica in place to play while you play guitar or another instrument with your hands. I got this along with the Johnson BK-520-SET Blues King Harmonica Set, although it usually doesn't come with the holder itself as far as I'm aware of. I got it on eBay so I think it was just a deal that this was included. I'm not sure if this would fit harmonicas larger than your standard diatonic ones like those found in the aforementioned set, as those are the only that I've used and there isn't an ample amount of wiggle room available. Since getting this along with the harmonica set I've unfortunately had to upgrade my harmonica holder as this one really isn't the best. I don't know what it's made from but it definitely isn't the sturdiest feeling. My main problem with it is that the screw will often get loose and fall down when I'm trying to play. I tried to keep it tight but it would get loose too easily and if you're playing live this can definitely be a problem. It makes it harder to play an instrument that I'm already not as familiar with as some others. While I could probably have made it work, I decided to buy a Hohner made harmonica holder which I find is a lot better. I can't complain too much since I did get this more or less for free with the Johnson BK-520-SET Blues King Harmonica Set, but it's just not the best harmonica holder around. It's definitely one of the cheapest that you'll find, but if you're looking for something to potentially play shows with and/or are playing with it on a lot, it's probably worth it to spend a few extra dollars on something like the Hohner.