Clearcom Single Muff Intercom Headset w. Female XLR Four Pin Connector Headphone: Amazon.co.uk: Electronics & Photo
StarTech.com 4 Position Microphone and Headphone Splitter – 3.5 mm – 4 Pin / 4 Pole – Mic and Audio Combo Splitter Cable (MUYHSMFFADW), White : Amazon.co.uk: Electronics & Photo
Peltor Hardhat Headset fitted with 4-pin female XLR (hardhat not inclu – Amber Sound
Canford/Tecpro SMH 210 Single Ear Headset (4pin) - Sonalyst