Fully adjustable for small, medium or large head sizes. Lightweight polymer plastic construction. 25dB noise level reduction rating (S.N.R). Wear them with ease for extended periods. Tested and approved to European standard EN352-1. Comfortable, balanced design. Reduces hazardous noise to harmless levels within 5 milliseconds. Hearing enhancement (up to 5x) greatly increases weak sounds. Independent volume control for each ear. Battery life of up to 200 hours. With audio input-jack for connection to two way radios. Suitable for shooting, hunting, construction, aviation, factory, motor racing, agriculture, police, military, etc.