JF-19 features Buffer and Tuner the Buffer saves the trouble of long audio cables or tone loss due to multiple pedals are connected in series.while the Buffer circuit retains the origina tone when multiple pedals are in use.Fits for 7-string guitars and 5-string basses thanks to its super fast reaction and highly accurate tuning algorithm,tuning accuracy:+/-1 cent real-time LED display enables you to read it clearly on dark stages.DC 9V Output Jack(Center minus).Besides,you can choose between True Bypass mode and True Buffer mode by the selector switch.