Plugin file used by SketchUp, a 3D modeling program used for computer-aided design (CAD); stores one or more Ruby scripts (.RB files) that are compressed with .ZIP compression; useful for reducing the size of SketchUp plugins when distributing and installing them.
SketchUp 8 was the first version to allow compressed RBZ plugin files. You can install them by following these steps:
Choose Window → Preferences.
Click Install Extension and choose your RBZ file from the open dialog.
NOTE: RBZ files can be restored to the original Ruby scripts by unzipping them.