Designed for stringed instruments with a floating bridge, and especially good for Maccaferri & Selmer style guitars, acoustic archtop guitars, bouzoukis & octave mandolins; and even cellos. The pickup is only 6/1000 of an inch thin and measures 1 3/4" x 3/4" total. It is a compression pickup because it is especially suited for wedged applications under the floating bridge. The pickup element is also capable of transmitting sound like a soundboard transducer, so the best tone is achieved if the pickup is mounted so it is partially wedged and partially open on the soundboard. The system also includes an endpin jack which can be mounted internally or externally as you prefer, and the "Definity outboard preamp" which focuses and strengthens the sound prior to sending the signal to an amp or mixing board.