From our research, this is an early 1978 version 3 pedal in very good condition given it's 40 years of amazing sounds. There is NOTHING like the sound of this pedal, and we have tried them all ! Of course this absolutely nails Police, David Gilmour, Robin Trower and a host of other classic tones of late 70s/early 80s, yet so much more versatility beyond that. This is a non-Deluxe Electric Mistress, which we have always preferred. Some argue, and we concur, this is the best Flanger ever made.
One thing we would like to point out is the fiber off one of the pots seems to have separated, presumably from taking the back off to change batteries. Is is still attached electronically and does not affect the performance or sound of the pedal in any way - we just want to point this out.
This is a 12v pedal, so if you use two 9v batteries is runs through regulation to knock it down. There are good quality 12v adapters that work fine with this old style AC input.