In a Class by Itself 
  Etymotic invented noise-isolating, in-ear earphones. The ER4 MicroPro series earphones were the first earphones commercialized using balanced armature  technology and are recognized as the world leader in response accuracy, to which all other earphones are compared. After more than 20 years, these reference-quality earphones are still the choice of serious sound engineers, audiophiles and musicians.
World leader in sound reproduction
Unsurpassed frequency response accuracy and sound quality — 92%+ response accuracy from 20 Hz - 16 kHz.
The only earphones with balanced-armature, precision-matched, custom-tuned drivers.
Highest output sensitivity in its class.
Timeless style and fit 
  Professional quality and reliability. 
An assortment of noise-isolating eartip options to ensure proper seal and comfort. CUSTOM•FIT option available.
Highest noise isolation 
First earphones to completely seal the ear.
98% (35 dB - 42 dB) noise isolation —highest of any earphones or headsets on the market today. 
Reduction of outside noise reduces the risk of listening at unsafe levels.