Like the B-Band AST and the K&K Pure Mini, the LR Baggs I-Beam is a soundboard pickup that adheres to the inside of your guitar, on the bridgeplate between your soundhole and bridge pins. In doing so, it produces a remarkably natural tone by picking up the vibrations of the soundboard (rather than the vibration of the strings, as with undersaddle pickups). The I-Beam is responsive enough that it will even pick up percussive effects and fingersqueak. Included with each I-Beam is a placement jig that makes the pickup totally self-installable (provided you have the hole for the endpin jack in place). I-Beams are shipped with extra adhesive strips on request in case you need to experiment with placement. While the I-Beam Active uses a 9-volt battery onboard to give it some juice, I find that it can really benefit from a good preamp like the Baggs Para-Acoustic DI.
This I-Beam pickup is available in two versions, one for regular steel-string guitar and one for classical guitar. The systems are essentially identical, but the classical version has a little arch cut into the middle of the pickup so it can straddle the center fan brace.