Amdek FLK-100 Flanger
The Amdek series of pedals was produced by Boss in the 80's as a DIY approach to pedals. They were sold as kits and generally used original Boss circuits. The PCB's came assembled and the buyer simply soldered the hardware and screwed the pedal into place.
The FLK-100 was a variation of the 80's MIJ BF-2 and has a similar tone and layout.