This is 4 step clean booster with passive bypass mode.
The QTB has 4 different level of gain control
- Low profile / True bypass @ Clean tone /  0dB /  6dB / 14dB / 20dB
  No switch poping niose / Long battery lifetime (3000 hours)

QTB works with passive, active pickup and bass guitars.
Only small amount of current drain (0.16 mA) required that means your 9V battery will last long for years
 (more than 4000 hours in continuous use. - workable voltage : drop down to 5 V).
Applications : Electric Guitar and Electric Bass Guitar