Amazon.com: StarTech.com 4 Position Microphone and Headphone Splitter – 3.5 mm – 4 Pin / 4 Pole – Mic and Audio Combo Splitter Cable (MUYHSMFFADW), White : Electronics
OFFROAD to 5-Pin Adapter (For Headset Direct Cables) by Rugged Radio – Pro UTV Parts
Adapter for Scanner to 5-pin Car Harness, Headset, or Intercom – Rugged Radios
6-pin LEMO Connector to GA Twin Plug Adapter (for Bose A20 Aircraft Powered Headsets)
How to repair fix handsfree headset earphone jack pin speaker not working - YouTube