Sony MDR-W24V Vertical In-The-Ear Headphones (Discontinued by Manufacturer) Lightweight Design With Soft Ear Cups 13.5Mm Driver Volume Control Sony Acoustic Twin Turbo Circuitry Frequence Response: 18 Hz-22 Khz Open-air, dynamic headphones which fit comfortably in the ear In-line volume control for quick convenience Sony's Acoustic Twin Turbo Circuit for high sonic output Neodymium magnets for max power and light weight 13.5 mm diameter for small size and sound quality