Sound is relayed to the user's eardrum not into the ears but via bone conduction through the skull.
Glass has a built-in microphone, which does a good job of picking up the voice of the wearer, but strains to capture sounds farther away. This is probably by design for both the privacy of non-wearers and also to improve the voice recognition of the user.
The right side of the Google Glass hardware is a touchpad, which enables users to control the device by tapping or swiping.
Glass connects to the Internet and any Bluetooth-capable phone via Wi-Fi and Bluetooth.
The battery should enable a day of moderate use on each charge, according to Google. However, using the video feature drains the battery much faster. One user estimated that a video recording of less than seven minutes drained about 20% of the battery power.
The camera takes 5-megapixel pictures and 720p video.
Glass comes with a Micro USB cable and a charger.
It comes in five colors: Charcoal, Tangerine, Shale, Cotton and Sky.
Glass runs Android, according to an earnings-call comment by Google co-founder and CEO Larry Page this week, although almost certainly a custom version of Android rather than the same version that runs on smartphones. In other words, Android smartphone apps won't run on Glass, and (presumably) Glass apps won't run on Android smartphones.
Glass comes with an Android-only app called MyGlass, which among other things enables SMS and GPS messaging. MyGlass for other phone platforms could come later.
An analysis of MyGlass reveals multi-player game support, although it's possible that it's there for Android in general rather than Glass in particular.
Developers can create apps, which Google calls "Glassware," using Java or Python plus what's called the "Google Mirror API," and a set of services called "RESTful" for conveying messages to and from the Glass devices.
How it works
The Google Glass user interface is based on "cards" -- discreet chunks of information similar to cards on Google Now -- and these exist in a timeline, which users can navigate via a swiping gesture on the touchpad.