Viborg seems to make some pretty good stuff that they sell at relatively low prices. Here is an example of their pure copper blade ac plugs. They also make other types of wire connectors and other stuff.
Furutech's Alpha is a two-step process that they apply to a variety of metals. The process (described here) involves:
- deep cryogenic freeze
- Ring Demagnetization treatment
The various metals/conductors used by Furutech that may undergo Alpha treatment, include:
- PCOCC: α (Alpha)-OCC conductor
- PC-Triple C: α (Alpha)-triple C conductor
- Nano liquid infused OFC: α (Alpha) Nano-OFC conductor
- Silver and OCC copper alloy conductor: α (Alpha) silver OCC hybrid conductor
- μ-OFC: α (Alpha) μ-OFC conductor