Compared to the BM series, a longer string post and a larger button plus a bigger baseplate make it a perfect replacement tuner for models JB and PB. Counterfort-mount. Gear ratio 1:20. All parts are precision-crafted and surface-finished, the self-locking drive ensures an even, delicate and steady tuning. All string posts are made of high-grade brass and fitted into the housing with utmost precision, ensuring the best possible tuning accuracy and wear resistance. Features: Model: Open-4 left, Mounting: 4 Screws/Thrust bearing, Buttons: .27, Surface: Chrome, Ratio: 1 : 20, Weight g/item: 103, Bore mm: 14