Sennheiser HD 300 PROtect Overview The Sennheiser HD 300 PROtect are closed-back, over-ear studio monitor headphones offering high-resolution audio reproduction and switchable peak level protection for musicians, audio engineers, and event staff in broadcast, studio, and live stage applications. The precision-diaphragm dynamic drivers produce a wide frequency response of 6 Hz to 25 kHz with low distortion and a maximum SPL of 123 dB. Switch on the Active Gard hearing protection technology to limit levels above 110 dBA for safe listening even with unpredictable source volumes. The HD 300 PROtect's circumaural, closed-back design provides up to 32 dB of passive isolation from ambient noise. Thick ear cushions and headband padding ensure comfortable wearing for long listening sessions. The detachable 4.9' single-sided cable is terminated with a 3.5mm stereo mini jack, and may be swapped for other Sennheiser modular cables (available separately). A 1/4" TRS adapter is included to allow easy connectivity with mixers, dedicated headphone amplifiers, and audio interfaces. The HD 300 PROtect headphones fold for compact storage and transport.