• 16 to 23,000 Hz frequency response
• Deep bass performance
• 4-foot cord

Koss The Plug is a stereo earbud for the discriminating listener. It delivers accurate acoustical reproduction and unbelievable isolation typically found in more expensive, closed-style stereophones. The Plug features a dynamic element that is positioned just outside the ear and connected to a tubular port structure that is inserted on a soft expandable cushion into the ear canal. The soft foam cushion expands for a custom fit to improve isolation and enhance deep bass and treble clarity.The Plug has special ear cushions made of hydrophilic, formed urethane, for a custom fit each and every time it is inserted into the listener's ear. The custom fit enhances isolation when you want to plug out ambient sounds that interfere with the listening experience. The Plug delivers the full sound of Koss. Combined with your favorite music and a portable sound system, it is the ultimate accessory on the go. A mute switch on the cord provides connection to the outside world without having to un-plug.

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.

Not worth even the twelve bucks...the buds I got for $2 on my last plane ride have as good a sound and are more comfortable.

Note: I received a a black model. Also, they are ported (holes on the outside of the housing to allow pressure transfer, but which don't seem to diminish noise isolation.

Pro: The noise isolation with these is great: The eartips are the squishy foam, just like Hearos and other earplugs. The result is a really good seal with your ear canal. When riding the bus or walking around, I am able to turn my iPod down from 50-70% volume to around 10-20%. It's a huge difference.

Con: The cord is composed of a spongy, grippy rubber. It's the perfect material to use on those dashboard grips you see advertised, where you put something on it (like a cell-phone) and it stays put. However, for a cord it's annoying, as it prevents you from wrapping it, and it just feels stiff and icky. The cord also transfers a lot of vibration noise to your ears when you are in motion. Maybe this is normal for all ear-canal headphones? I don't have enough experience with them. It's my guess that a less stiff, springy material might have been better.
Solution: run the cord for one ear over the back of your neck (if your neck is small enough) as it will reduce the pull on your ears.

I like:
- Quality sound.
I do not like:
- Easily drop of my ears
- I have to squeeze hard to fix the ear and it bothers.

I have started working out, and other headphones would fall out of my ears ~ these stayed in perfectly, and blocked the gym music and other gym noises. Plug into my iPod and get lost in my music ~ and comfy also!
No falling out during crunches or jogging, earbuds stay in place.

If you can get past the Frankenstein look when you have these things plugged into your ears, you will love these. They're actually very comfortable when you put them in because of the memory foam style pads. If you have a smaller earhole like mine that don't hold the typical hard plastic style earplugs all that well, these are the ones you want to get. I've fallen asleep with these on plenty of times they were so comfortable, & not once did I have the soreness that I get in my ear that I get with some other style earplugs. Sound quality is nice, especially the bass which is not too thumping but nice & crisp, which is the way I like it. Don't expect audiophile quality sound but for the price you will be more than happy with these.