The AirCurve ships in four glossy, black parts: the dock itself, a 3.5-inch plastic arm that connects to the dock with a ball-in-socket joint, and a pair of plastic mounting clips for windshield and dashboard mounting.
The AirCurve grips the iPhone with two, spring-loaded arms, which hold the handset in place over a pair of rubber hollow contact points. Between those lower contact points is space enough to connect the iPhone's dock connector for charging. One of the contact points (left) covers the iPhone's internal microphone, allowing sound to pass to the phone unmolested. The other (right) contact funnels sound from the phone's speaker into the AirCurve's passive amplifier.
The passive amplifier is old and low-tech -- almost 135-year-old low-tech. Essentially, it works like the horn on a 19th century phonograph, accepting the sound at the narrow end of a hornlike passage, snaking through the body of the AirCurve, and channeling it out of the wide opening just to the right of the phone mount.
Griffin claims a 4x boost in speakerphone loudness and a max amplification of 25 dB. I did a before-and-after test in the quietest vehicle on hand in the Car Tech garage, the 2012 Toyota Plug-in Prius. Measurements were taken using a second phone running the Smart Tools app for Android's Sound Meter function. The bare iPhone 4S output a measured average of 56 dB. When we placed the phone in Griffin AirCurve, the measured loudness jumped to 68 dB. So the AirCurve doesn't exactly make its 25 dB loudness boost claim, but to my ear it's still substantially louder. Griffin's not just selling snake oil here -- the AirCurve really works.