Super Time Line digital delay. A staple of the eighties clean and sturdy also easy to use. This unit also allowed for storing 4 preset, a big deal in the early days! Well mine stopped working, still passed signal but no effect. I realized the internal memory battery was probably at fault and sure enough it had leaked all over. Fortunately it hadn't taken any other components with it or eaten through the PCB. So new Varta battery and as good as new. Man this thing sounds great!