Military grade dual circuit boards. Gold Connectors for high quality audiophile sound. Automatic shut off. Pro Form Leather ultra comfortable ears seals. Behind the Head Headband. Amplifies sound more than 8x normal hearing. * Weighs only 9.3 ounces. Fast attack time of 1.5 milliseconds. Includes 4 N size batteries. 3.5mm input jacks for i-pod and MP3 players. Battery life is 250 hours.