Features: Safety Helmet Mounted: easy to clip on a hard hat, and fits most hard hats.  Sound Insulation: Designed with 2 layers of professional noise dampening foam, high sealing solid cup, the earmuffs has good sound insulation effect, no more bothering by noisy noise.  Functional: a simple way to improve sleep quality, reduce noise damage to hearing, avoid noise interference and effectively improve work and study efficiency.  Reliable Quality: ABS shell, 304 stainless steel headband, good resistance to corrosion, heat and oxidation.  Ergonomic Design: soft good tightness ear cushion, comfortable to wear.  Wide Application: for sleeping, shooting, in flight, factory, construction site, etc.   Specifications: Material: ABS+nylon+SS+sponge;  NRR: 23dB;  SNR: 28dB;  Class 5 SLC (80): 29.5dB;  Item Size: 21 * 15cm / 8.27 * 5.91in;  Item Weight: 307 / 10.83oz;  Package Weight: 315g / 11.11oz;  Package Size: 20 * 14.5 * 9.5cm / 7.87 * 5.71 * 3.74in;   Package List: 1 * Ear Muffs