$no draw
... 
$no_draw is a material shader parameter available in all 
Source games. It is a setting that causes the material to not be drawn or rendered at all. Usually used to quickly hide parts of a model, without having to make a transparent texture.
Similar to the Nodraw tool texture for maps, except this can be applied to models. This can be used as a workaround to the broken "Removemodel" on $lod
Example
VertexLitGeneric
{
$no_draw 1
}