The Senal SMH-HMM is a replacement cable intended for use with SMH-series communication headsets. It can also be used to augment your headset's versatility, giving you the ability to plug into a PC or laptop.
At one end, you'll find the 3.5mm TRRS connector and corresponding locking jack. This twists into your SMH-1010CH or SMH-1020CH communication headset, establishing a secure and reliable connection all the while.
At the other end, you'll note two more 3.5mm plugs. With these connectors, you can monitor audio from your PC or laptop's headphone jack while simultaneously looping your headset's microphone into the computer's mic input.
The SMH-HMM is part of a whole ecosystem of SMH-series cables, all of which let you swap between the pin-outs of different computer, communication, and broadcast systems with ease.