The PTL (Push-to-Listen) listen-only hard hat model headset offers safe attenuation with the push of a button. This comfortable and durable communications headset allows for long-term use under exacting conditions. also features: Earcup button for listening mode, listen-through capability with the pass-through sound limited to 87 dB, auto-switches to full protection after 30 seconds or when button is pressed again, earcups with liquid and foam-filled comfort cushions for long wear and optimum seal. NRR 25dB*. *The NRR may overestimate the hearing protection provided during typical use. 3M recommends reducing the NRR by 50% for estimating the amount of noise reduction provided.