Monster's Sigma Retro cables are carefully manufactured with ultra-pure 99.9999% copper. It is then put through a special annealing process to give it the finest conductive properties, while staying flexible and corrosion-resistant for the purest and most detailed midrange. Sigma Retro's advanced proprietary insulation materials have also been chosen with specific care. First, patented MicroFiber® is wound around the various wire networks to provide proper isolation and protection from contact generated noise, to ensure the quietest background and the greatest freedom from cable-generated noise. Then a distinct cross-linked polymer dielectric, PEX-2®, is pressure-extruded using laser-controlled precision dies to the precise dimensions to produce the insulation, which reduces capacitance and ensures stability for a wide range of frequencies. Since PEX-2 does not chemically react with copper, it guarantees that the impeccable high frequency performance will not degrade by corrosion at the copper surface. Lastly, the Super MultiTwist construction rejects audio bandwidth distortions for greater clarity and imaging. For the best possible connection, Monster's Sigma Retro speaker terminations feature 24k platinum/gold contact alloy spade connectors. These spades are flat on one side for maximum contact area, and Turbine® textured on the other side for a secure clamp to the binding post. Sigma Retro Interconnect Cables offer a stylish 24k gold contact RCA connector housed inside a termination which resembles a jet engine.