Etymotic Research ER4SR Studio Reference In-Ear Earphones

Unsurpassed frequency response accuracy & sound quality - 92%+ response accuracy from 20Hz-16 kHz
The only earphones with balanced-armature, precision-matched, custom-tuned drivers
Highest output sensitivity in its class
Professional quality and reliability
An assortment of noise-isolating eartip options to ensure proper seal and comfort
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