The Official MX RAY headphone cable.  We proudly include this cable with our headphones.  It is a 16-core cable (8 cables for each side), which improves fidelity and reduces cable resistance.  The cores are also twisted pairs, reducing interference and noise over the length of the cable.
 
Compatiblity: MF-1, CF-1, any headphones with 2x 3.5mm connectors