B-KNOB series: this series comes from a good idea about rotary knob. When your pre-amplifier is powered on, the top surface of the rotary knob will emit very cool blue halo. Here the laser engraving technology is applied to process the characters and transparent zone on the top surface of the rotary knob. You may press the rotary knob and it will bounce up automatically. Then you may rotate to adjust the parameters of the pre-amplifier. When you don’t use it any more, you may press it down to collect the whole rotary knob. It’s easy for you to open the LED tuner that matches with the product to help calibrate the guitar. The whole series adopts the piezo pickup of 0.8 mm thickness that is made in soft knitting process, which allows you to rapidly and accurately install without the need of excision processing of saddle. This kind of piezo pickup is of good and natural bass and clear treble, which makes the whole voice natural and balanced.