Boss Digital Delay RDD-20 Book and oxidation of the metal

and oxidation of the metal panel where the sliders are

this one is over-keen to self-oscillate - starting to get fruity at anything at settings from about 9-10 o'clock onwards: this isn't a problem as you can still back off to very low single repeats

The isolator section comes with a frequency switch that enables DJs to switch the cut-off frequency and a boost level switch located on the rear panel

and it's perfectly possible to get either no signal at all or speaker-shredding frequencies

it comes in the original box with the owner's manual

Boss Digital Delay RDD-20 Book and oxidation of the metalClassic Boss Micro Rack delay with modulation. Tested and working as it should.