For HMT-1 and HMT-1Z1. Intrinsically safe (IS approved) for use with the HMT-1Z1 in hazardous locations. The Tri-Band Strap is a head strap for the HMT-1 and HMT-1Z1 that replaces the standard Overhead Strap for a more secure fit. The Tri-Band Strap supports greater maneuverability and mobility, and ensures superior fit and positioning of the HMT-1 and HMT-1Z1 over a wider range of head sizes and shapes. The Tri-Band Strap is also needed to mount the HMT-1 when wearing a bump cap or baseball cap. Shown with Bump Cap and HMT-1, not included.