$cbox
$cbox is a QC command available in all 
Source games. It sets the clipping bounding box for the model. This box is used for the culling of models in the game for optimization.
A model will be culled as soon as the clipping bounding box is no longer in view of the camera.
If the coordinates of the clipping bounding box are all zero, $bbox is used instead.
Syntax
$cbox (min x) (min y) (min z) (max x) (max y) (max z)
