Hammer Collision Detection

[Porygon]

Is there a way to make just a wall of invisible collision detection in Hammer, other than just making a blank wall and putting a transparent texture on it? I'm having a weird thing happen where I can't see an imported object behind the typical invisible wall for some reason, and this is the only other way I can think of dealing with it without changing how I'm doing things.

Thanks

[Borsty]

clip or blockbullets material?

[Num Lock]

Playerclip texture.