Koss CC_01 isolating in-ear headphones feature a unique, custom fit experience. Rotate the dial and the ear cushion expands to provide perfect fitting in-ear headphones with great sound. It's an entirely new state-of-the-art ergonomic and acoustic design. Koss in-ear headphones are designed to produce a perfect seal. This seal allows the variable matched transducer to directly couple with the eardrum. This direct response system means greater acc...