|JVC HA-FX66 Press Release wrote ...
"The HA-FX66 headphones tackle that problem by using a soft silicon rubber air cushion for the earpiece body. In addition, the headphones come with three different size silicon rubber and memory foam cushion earpieces for the best possible fit. The result is an in-ear headphone that stays securely in place while remaining comfortable. What's more, the design also provides superior isolation from background noise, allowing the user to get the most out of the headphone's 8.5mm neodymium driver. Noise caused by cord movement is also minimized because of the headphone's Friction Noise Reduction Cord vibration-proof structure."