Denon AH-C252K In-Ear Headphones (Black) (Discontinued by Manufacturer) Acoustic Optimizer sound pressure balancing technology 11.5mm diaphragms with Neodymium magnet drive units Comfortable in-ear design, helps block out external ambient noise. Wide frequency response 20 Hz ~ 23 kHz Gold plated 3.5mm mini plug, compatible with iPhone 3 detachable ear pad pairs included (S, M, L) for optimum fit and comfort