Sennheiser HD-300 Pro, Monitor Headphones, Closed, Circumaural, Impedance: 64 Ohms, Nominal sound pressure level: 108 ± 3 dB SPL / 1 V rms / 1 kHz, Transmission range: 6 -25000 Hz, Harmonic factor <0.1% at 1 kHz, Boundary sound pressure level: 100 dB, Nominal load capacity: 500 mW, Pressing force: 6.0 N ± 0.75 N, Single-sided cable in 1.5m length with 3.5 mm jack plug, Weight without cable: 297 g, Includes 6.3 mm adapter