Bilsom's® Thunder® series earmuffs have a dielectric construction to protect workers in electrical environments, and designed with all-day comfort in mind. Can be mounted on a wide range of hard hats. Earcups snap in place during use and swing back when not in use. Includes a pair of adaptors for use with popular hard hats. Features patented Air Flow Control™ technology for optimal attenuation across all frequencies and also snap-in ear cushions for easy maintenance.