Dated to 1982, serial # 2010768. It takes TWO 9v batteries in the back for the active circuit. When you flick the switch to turn on the active circuit, it nearly doubles the output from the two hunbuckers. The active EQ has a wonderful scope, going from a deep growl to a bright top end, with everything in between. The bottom switch turns the active circuit on & off. The middle is a phase switch (bridge p/u only). The top is a coil tap switch for both p/u’s. The bottom knob is volume for the active cicuit. The middle knob is for EQ (both active & passive). The top knob is for volume (passive).