Product Features and Technical Details
16 to 23,000 Hz frequency response
Deep bass performance
4-foot cord
Technical Details
Brand Name: Koss

Headphones Form Factor: Ear-bud
Headphones Technology: Binaural
Item Weight: 0.31 pounds Koss's miniature portable earphone, affectionately dubbed "The Plug," makes use of an ear-cushion material (similar to that used in sound-blocking earplugs) that slowly expands in your ear canal to provide a custom fit and maximum sonic isolation from external noises. A detachable, extrawide headband makes these Koss-termed "stereophones" easy to carry or store.
For accurate sound reproduction, these earbud-style headphones are made with oxygen-free copper voice coils and neodymium iron boron magnets. You can enjoy them with either a portable or home audio device, since both 0.125-inch and 0.25-inch adapter jacks are included.

"The Plug" weighs a mere quarter ounce and has a frequency response rated at an impressive 16 to 23,000 Hz (though its unlikely you'll hear bass output anywhere close to what you'd get from a similarly rated loudspeaker!).

Impedance is 16 ohms, with less than a 0.3 percent distortion and reasonably high sensitivity of 112 dB SPL/1 mW.

Product Description
Unique earbud design directs sound into the ear canal for deep bass and extended frequency performance. Specialty ear cushion material forms slowly in the ear canal to provide a custom fit and maximum isolation. Straight, dual entry 4 foot cord. Frequency Response: 10-20,000Hz.