The E-Max amplifies sounds below 85 decibels, which amplifies normal communication, range commands, and environmental sounds. Above 85 decibels, the microphones shut off for a split second to protect the shooterâ??s hearing. Two microphones â?? one in each cup â?? give the user true stereo sound and allow the user to identify the directional source of a sound. Includes an integrated audio input jack allowing music to be played. Runs on 2 AAA batteries (not included). 23 NRR