Etymotic Research ER4SR / ER4XR Earphones

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. Backed by decades of research and development for the ear 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 Features Professional quality and reliability Precision-matched, custom-tuned drivers Precision machined metal bodies with anodized finish Detachable, reinforced 5 ft. cable with 3.5mm gold plated stereo plug and MMCX connectors Assortment of noise-iso