Styled in a closed-back design, the RPmk3 Series T40RPmk3 from Fostex comprises a pair of stereo headphones. Their copper-foil etched polyimide film drivers utilize proprietary Regular Phase (RP) technology in order to ensure an accurate reproduction of sonic material, thereby rendering these closed-back headphones suitable for monitoring in studio situations. To ensure a full representation of the sonic spectrum, these headphones have a frequency response of 20 Hz to 35 kHz.