Tool textures (Source)

The tools textures can easily be found in Hammer by running "tools" as a filter word in the texture browser. These textures have extra attributes that most textures do not.

Note: Here's a tutorial on using many of the Source Tool textures shown below [1]

Image	Name	Special attributes
	Area portal	Use with func_areaportals and func_areaportalwindows
	Black
	Block LOS	Blocks the line-of-sight of NPCs and bots
	Block bullets
	Block light	Invisible; casts shadow like standard materials
	Clip
	Player clip control
	Fog
	Hint	Breaks up visleafs
	Invisible	Solid to all objects, invisible and does not cast shadows
	Ladder
	No Draw	Solid; Invisible; seals leaks; blocks visibility if used on all surfaces of the same brush
	NPC clip	Solid to NPCs but not players or other objects
	Occluder	Use with func_occluders
	Origin	Use to set the rotation origin of rotating entities; obsolete in Source
	Player clip	Solid to players but not NPCs or other objects
	Skip	Invisible; has no effect on anything
	Skybox	Use to make skyboxes
	SkyFog
	Trigger	Use on Trigger entities and Buyzones in Counter-Strike: Source. Also don't forget to move the selected trigger brush(es) ToEntity so you can change the properties.