Fishman's Rare Earth Pickup, Designed and Voiced Specifically for Bajo Quinto, Warm Full Humbucking Sound, Volume Control Wheel, Active Electronics, and Neodymium Magnet Structure for Exceptional String and String Balance and Brilliant Acoustic Clarity, Low-Bass Preamp Design current allows up to 240 hours between battery changes, pre-wired output jack can also be endpin mounted, easy no-alter installation, plug-and-play right out of the box, fits soundholes as small as 3 5/ 8” (92mm) in diameter, uses 2 x 1.5V silver oxide batteries or one 3V battery.