Heavy Industry reduces the sound level by 25dB making it safe for 8hours continuous use in any environment up to 110dB. All Crescendo Industry protection can be combined with earmuffs in very loud situations where double protection is a requirement. While other hearing protection can sound muffled and unnatural, the Industry range uses advanced membrane technology from Dynamic Ear Company that provides an air passage to the ear, minimizing the occlusion effect whilst keeping the ear ventilated for optimum comfort. ANSI and CE marked with an SLC80 of 22dB (Class 4) for WPHS confidence.