The Dunlop Ultra FBR2 Feedback Buster is an accessory for acoustic/electric guitars that reduces the amount of feedback you get and therefore gives you more control over your level. Hot pick ups will definitely give you a bit of feedback when plugged in. The FBR2 is designed for playing acoustic guitar for live shows rather than in the studio, as it's definitely not best for the studio since it covers up the sound hole. This will fit any standard size acoustic guitar hole as far as I know, but definitely double check before buying. There's really not much to this here, as it is what it is. There aren't any controls or anything at all as it's just a simple piece of what I think is rubber and it fits right into your acoustic guitar's sound hole. For this reason it's a real inexpensive way to get the job done. It's probably not going to be necessary unless you're playing a lot of shows in larger venues where it's possible you're going to get a good amount of feedback from your guitar. In smaller settings, or if you're just using a small amp, you're most likely not going to get much noise or feedback. Either way, the Dunlop Ultra FBR2 Feedback Buster is cheap enough where it's worth looking into if you think you may need it at all. I've got one of these at home for use with both my Guild and Martin acoustic guitars, although I don't need to use it all the time. I don't know how this would compare to other products of it's type as this is the only feedback buster model that I've used. It's definitely a nice and cheap tool to have around, but won't be necessary for the majority of acoustic guitar players.