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.

ER-4P (Portable) earphones can be used with iPods, portable CD, MP3, DVD and other players without requiring an additional amplifier. As compared to the ER-4S, the ER-4P has 10 dB greater output at high frequencies and 13 dB greater output at low frequencies. The higher sensitivity and enhanced bass of the ER-4P have made it the most popular earphone for most uses.

• In-the-ear secure fit for optimal performance
• Highly accurate music reproduction with greater sound output and enhanced bass

System includes:
• ER-4 MicroPro earphones
• 5 ft. cord with 3.5 mm stereo phone plug
• 1/4" stereo phone adapter plug
• Six 3-flange eartips
• 10 foam eartips
• Filter changing tool
• 4 replacement filters
• Shirt clip
• Pouch

ER 6i Technical Specifications:
Frequency response: 50 Hz- 10 kHz +/-2dB; 20 Hz -16 kHz+/-4dB
1kHz sensitivity: 102dB Impedance: 27 ohms
Maximum output:122 dB SPL
Weight: less than 1 oz.
Warranty : 2 Years