Electro-Harmonix LPB-1 Linear Power Booster. This is a later production unit of the first generation inline design. It most likely dates from the mid to late 1970s (1975-1978). It is hand-wired. After 1978 they had PCBs. The jack has “Japan” stamped on it which indicates it’s not an early production unit (1968-1972) which used Switchcraft jacks. The plastic knob is non-original. Unit works properly. No scratchy pot.