1. Sig Sauer SIG SAUER - Axil TRACKR™ Passive Ear Muffs

2. Neckerchieves, bandanas [neckerchiefs], warmth-keeping supports, mufflers, ear muffs [clothing]

3. Hearing protectors — Safety requirements and testing — Part 5: Active noise reduction ear-muffs

4. Hearing protectors - Safety requirements and testing - Part 5: Active noise reduction ear-muffs