The Neotech NECH-3001 is a headphone cable made of 4 multi-strand UP-OCC Copper Litz conductors with PVC insulation and a Nylon braided outer jacket.
Litz means that each strand of copper is polyurethane coated; this reduces the impact of the skin effect and the proximity effect - great for audio, but the coating must be removed before a good solder joint can be achieved. This is best achieved using flux and a solder pot to tin the ends. Alternatively, tin your soldering iron with lots of solder and run the wire through the solder on the iron, the coating will melt and you can scrape it off.
Price (per 0.5m)
£11.53 +vat +p&p