IeGO Dreamworks are manufacturers of audiophile-grade cables and connectors, and produce some of the best connectors available – regardless of price.
They use pure Furukawa copper as the base material for all their connectors; unlike many of their competitors, who use phosphor bronze and brass (which is not as good a conductor as pure copper).
The copper is acid-bathed to remove impurities and the entire connector is deep cryogenically treated to relieve internal stresses within the material, which also improves conductivity. The gold-plating is vapour deposited and helps to stop the copper from oxidising, and also adds a certain warmth to the sound quality.
Available as a pure copper IEC plug, as well as silver-plated, gold-plated and rhodium-plated.