This is a custom headphone replacement cable (6.35mm on one end, 3.5mm on the other). It allows for a direct connection between headphones with a 3.5mm jack and a 6.35mm jack on a CD player, etc. The 3.5mm mini-plug is a REAN NYS231G, and the 6.35mm connector is an AMPHENOL/ACPS-GN. The cable is a 3080 microphone cable, 5mm in diameter. This is the thickest cable possible for headphone use, and the mini-plug was custom-modified for it. Replacing the original cable on my ATH-S220BT BK results in higher resolution and clarity, allowing you to feel the quality of the instruments. It reproduces the sound of CDs in detail. *I can make cables of any desired length. Please request a custom length via the question form.