You'll want the Roland GA-FC foot controller for your Roland GA-112 and GA-212 guitar combo amplifiers if you want to get the most out of them.You can switch instantly between all four channels, or even change the signal path for the effects loops and reverb.And for ultimate control, just connect up to two expression pedal (sold separately), for complete control over drive and volume settings.Hey, a rockin' four-channel amp like the GA-112 and GA-212 needs comprehensive control to keep up with you - so get the Roland GA-FC foot controller from GearNuts.com and hit the stage!