Donner DT Deluxe Guitar Chromatic Tuner Pedal &plusmn; 1 Cent 1.New super fast precise strobe mode with +/- 1 cent accuracy. 2.Chromatic which is suitable for wide range tuning. 3.Deluxe LED display leads clear results of tuning. 4.True bypass, improved analog circuit, real signal, no loss of tune. 5.Power Supply: DC 9V (negative in the center ) Power Supply9V DC (Negative in the center). LED LightLED indicator shows the working state. Input &amp; Output JackAnalogy though 1/4 mono audio jack Full metal shellAluminum-alloy classic, stable and strong. True BypassTrue bypass for zero tone coloration.