Product Description MONITORING HEADPHONE with ultra-linear response 64 ohm, on/off selectable Active Gard limiter, 1.5m cable with 3.5mm jack. The HD 300 PROtect adds Sennheiser’s patented ActiveGard technology, for advanced protection from peak levels above 110 dB. With ActiveGard, disruptive or harmful peaks are brought down to a safe level, preserving clarity and control at all times. The HD 300 PROtect satisfies European EC noise directives on industrial safety and noise control while safeguarding hearing for all production staff, even in the event of big surprises. From the Manufacturer The HD 300 PROtect adds Sennheiser’s patented ActiveGard™ technology, for advanced protection from peak levels above 110 dB. With ActiveGard™, disruptive or harmful peaks are brought down to a safe level, preserving clarity and control at all times. The HD 300 PROtect satisfies European EC noise directives on industrial safety and noise control while safeguarding hearing for all production staff, even in the event of big surprises.