HD 201 from Sennheiser is a compact closed-back dynamic headphone for monitoring and critical listening. The transducer has an impedance of 24 ohms and a sensitivity of about 104 dB SPL at 1 mW. The frequency response is 18 Hz to 18 kHz. A roughly 2 m cable ends in a 3.5 mm stereo plug with a 1/4 inch adapter. The design prioritizes robustness for event environments while providing accurate audio reproduction.