True Bypass, it mutes the guitar when you tune it so you don't have to hear your self tuning.Love this pedal. When its out of tune its Orange. When its in tune it turns Green so on stage you can clearly see it.
Let's be honest a tuner is really important on your board and nothing is worse than not being able to see that darn light to know if you're in tune or not. This pedal has a huge light up display that will be completely orange if you are not in tune and fully green when you are. I think it's a great one to have in a live setting as there will be no chance of mixups and it's real easy to see even with a bunch of lights and other stuff going on around you!