FISHMAN FULL CIRCLE 1/4-20, Double Bass Pickup, for UNC 1/4-20 threads, pickup with adjustable wheels. Plug in the Full Circle and the sound of your upright is all there. Whether it’s big, fat and punchy pizz, full-voiced arco or slap, you’ll hear all the acoustic qualities, dynamics, and nuances of your bass - only louder. Encased in a sturdy aluminum height adjuster wheel, the Full Circle offers accurate, transparent sound. To match the pickup to your instrument and playing style, a fine-tuning feature lets you quickly choose between an open, resonant response or a drier and more focused amplified tone. The Full Circle is a quick retro-fit on upright basses with height adjustment wheels. A Pro-EQ Platinum Bass, Pro-EQ II or B-II preamp is recommended, but not required. Professional installation is recommended.