The Unique Helmet Bone Conduction Headset PTE-129 uses skull bone vibration for sound transmission, and its unique shoulder strap design fits inside 99% of helmets. It has an environmental PU cable reinforced with Kevlar (sturdy and tensile) and an IP67-certified quick-release PTT (large button for emergency responsiveness), suitable for fire fighting, rescue, mining, chemical engineering, etc. Note: Specifications according to customer requirements, welcome to customize!