The ER•4 MicroPro™ earphones are the next best thing to live music, with noise isolation far surpassing that of active noise-canceling earphones. The ER•4s require NO batteries, and can be plugged into any audio source. Their external noise exclusion -- 35 dB with 3-flange eartips, 42 dB with foam eartips -- allows you to hear the full dynamic range of recordings without having to play them at unnaturally high and unsafe levels. The earphones come in three styles: ER•4B, ER•4S, ER•4P.
