Electro-Harmonix Holy Grail Plus Reverb Pedal Controls: Blend, Amount, and Reverb Type (Hall, Room, Spring)1/4" input and outputDC power input for battery replacement.LED indicates whether effect is engaged or bypassed. The Holy Grail Plus Pedal from Electro-Harmonix adds room reverb and a multifunction decay/damping/modulation speed control The Grail just got even more divine