Amazon.com: TNP 2.5mm to 3.5mm Adapter Cable (3FT) - Bi-Directional Male to Male 2.5 to 3.5 Subminiature Stereo Audio Jack Extension Converter Cable Gold Plated Headset Headphone AUX Connector Wire Cord Plug :
Sennheiser 6.3mm Female to 3.5mm Male Adapter Cable