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Electro-Harmonix Electric Mistress Flanger / Filter Matrix V3 1978-1979. This is my determination based on the number on the PCB board and clipped corners as shown in the photos. If any question or dispute on that please contact me. Power supply is not included, I tested this with the two 9V batteries and it worked and was fully functional but no express warranty beyond that. I'm the original owner and bought this new and used it but it has been in storage for a number of years just time to let it go to a new owner. I'm listing this conservatively as good but it is probably better than that, please look at pictures closely.
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