Caldwell E-Max Low Profile Behind the Neck Electronic Hearing Protection Green. The two microphones in this Hearing Protector from Caldwell will amplify sounds below 85 decibels which amplifies normal communication range commands and environmental sounds. Above 85 decibels the microphones on the Caldwell E-Max Ear Muffs shut off for a split second to protect the shooter's hearing. Two microphones - one in each cup - 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). 23NRR Specifications for Caldwell E-Max Low Profile Behind the Neck Electronic Hearing Protection: Manufacturer: Caldwell Color: Green NRR: 21 dB Features of Caldwell E Max Low Profile Behind the Neck Hearing Protection Muffs: True stereo sound for better localization Low Profile earcups reduce contact with gun stock Padded adjustable headband Volume control knob Power indicator light Fold compact Package Contents: Caldwell E-Max Hearing Protection - Low Profile 487605 Caldwell 487605: E-Max Low Profile Behind the Neck Electronic Hearing Protection Green