The Honeywell Sync Radio Hearing Protector has Digital AM/FM/MP3 and AUX input jack to connect to an MP3 player, mobile phone or other personal listening device. It offers high-fidelity sound quality on par with professional headphones. With Volume Management Technology, it manages sound levels reaching the user's ear to a safe level. Its Air Flow Control Technology delivers optimal attenuation across all frequencies without having to increase earcup size. And the technologically advanced acoustical bass chamber (patent pending) enhances bass sounds that are typically sacrificed in a stereo earmuff. The Honeywell Sync Radio Hearing Protector with Digital AM/FM/MP3 give you the ability to preset up to 10 radio stations. In addition, they offer one of the highest Noise Reduction Ratings [NRR 25] available in an electronic earmuff. It Includes a 3.5mm input cable to connect to most personal listening devices and two (2) AA batteries.