i have read
https://developers.google.com/glass/develop/gdk/quick-start
We recommend installing the ADT Bundle for easier development. The rest of these steps assume you have this installed. Click Window > Android SDK Manager. Install the SDK Platform and Google GDK Sneak Peek for Android 4.0.3 (API 15). Everything else is optional.
but at my Sdk manger i cannot find it,i also update my Sdk manger,but also not found.

