Puro Limiter 3.5 mm auxiliary audio cable keeps the volume 85dB and below. This cable now has a built-in microphone so when the headphones are turned off and being used via the cable you are able to use the microphone in the headphone. 

The cable is 3 feet long. Make sure you insert the correct side into your headphones, there is a direction arrow on the knob showing which side goes into the headphones.