Let’s be clear about one thing up front: if you want to blend into a crowd while using your iPhone, Apple’s white and gray packed-in earphones are fairly conspicuous in the sense that they stand out against skin and clothing alike, but they’re also now so common that people see them all the time without giving them a second thought. By contrast, iASUS Concepts’ 500K Series Headset for iPhone ($100) is a different sort of iPhone headset, and intended for a specific audience: law enforcement officials and those who want to look like them. Though it rates our limited recommendation, it does so chiefly due to that very narrow appeal, and commensurately high pricing.

Though 500K can be used to listen to music, it’s clearly not optimized for that purpose. Rather, it’s a wired communication accessory, designed to fit inside the canal only one ear at a time, using an FBI and CIA-grade coiled loop earpiece, and a professional-standard microphone and single-button remote unit that gets clipped to your shirt. As is understood by the Secret Service operatives who wear such headsets all the time, it’s the opposite of Apple’s earphones: initially invisible, but when people do see it, they’ll know what it means.
iASUS sells 500K in a package with several pieces: the coiled loop earpiece is first, either clear or black in color, making a physical connection to the microphone and remote unit at a rotating central joint.
This joint sits around neck level and attaches with a gunmetal-colored sturdy metal clip to a shirt collar to keep the earpiece in place; a second, matching metal clip holds the remote unit at your preferred shirt or inner jacket location. Left and right earpieces and a zippered carrying case with optional strap are also included. [Editor’s Note: Following our review, iASUS sent along additional parts that had been omitted from the original package: two large pink “contour earpieces” and a metal acoustic coil adapter.]
From a technical standpoint, there aren’t any huge surprises with 500K. The headphone plug fits recessed-port original iPhones as easily as flush-port iPhone 3G and 3GS models, and the components all feel as if they’ve been designed for extended use and reliability; the use of coiled cables and clips enables the entire chassis to expand to fit any sized user’s body. iASUS’s microphone box appears from a stuck-on label and fairly plain markings to be an OEM part, with its button rated for 500,000 presses, and the standard ability to stop and start music playback or telephone calls, plus track-changing if you tap the button quickly two or three times, and iPhone 3GS Voice Control initiation if you hold the button down. Callers said that the internal mic rendered our voices roughly as clearly from mid-chest level as an iPhone positioned directly next to our mouths, so although the mic’s performance will vary based on further distance and ambient noise, it did much better than we’d expected given its location.
This is the single strongest component of its performance, limited only by the fact that you need to worry about separately mounting the microphone and remote box on your body.
As an earpiece, 500K has one chief advantage and one notable disadvantage. The coil is comfortable and obviously visually designed to blend in rather than stand out, but as it uses air rather than wiring to pipe audio into your ear, the fidelity of the sound is only fair. For telephone calls, 500K is completely usable and loud enough for virtually any application—an in-line volume dial on the remote control box lets you reduce whatever the audio output level naturally is from the iPhone—but for music, it’s a mediocre performer and nowhere close to the sound of even Apple’s pack-ins. This is a headset for communications first, and audio listening a very, very distant second. Based on the unit’s modular design, lower-cost replacement of the earpiece coil is easy in the event that it wears out.
Finally, there’s the issue of pricing. iASUS has priced 500K at $100, which is unquestionably steep given the overall functionality offered here—again, you can get equivalent or better sonic performance out of the iPhone’s packed-in hardware—and a quick look around the Internet suggests that there are some companies selling comparable headsets for lower prices.