Astell&Kern Layla II In-Ear Monitors By Jerry Harvey Audio - 12 Drivers per channel, 4th Order Crossover, and Full Polished Titanium Housing Custom-made Proprietary Balanced Armature Drivers (12BA per side) Powered by soundrIVe technology : Quad low, Quad Mid and Quad High balanced armature drivers per side Variable bass output, adjustable from cable : user controlled low frequency drivers with the adjustable bass (0 - +13dB). Frequency ranges from flat bass response up to +13dB (10Hz to 100Hz) Integrated 4th Order crossover Noise Isolation -26dB