SPEAKERS AND AUDIO INPUT JACK: Equipped with full dynamic range HD speakers for clear balanced sound, it also comes with an audio input jack NOISE REDUCTION RATING (NRR): Delivering an impressive Noise Reduction Rating (NRR) of 23 dB, this muff is sure to protect your hearing, without interfering BUNDLE INCLUDES: Walker's Razor Slim Electronic Shooting Hearing Protection Muff (American Flag Distressed, Tan) and Walker's Crosshair Sport Shooting Glasses (Clear)