Soldano SLO 100-R. Extremely rare.. If looking, probably aware these virtually never come up for sale. Older SLO’s need a one button foot-switch plugged into the back to switch channels. A few extra holes drilled in back..not sure if those are factory and/or reversed mods etc..either way, doesn’t look like any alterations were done to the board..effects loop works as it should. Serial number indicates 1989 manufacture date. Amp sounds incredibly awesome.. slightly different character than my 2021 SLO.