Search and Mark

 is a perk in Fallout: New Vegas given to you while you have Rex as a companion.

With this perk, chems, firearms, and ammunition within a short distance are highlighted when you zoom in.

Openable containers (i.e. refrigerator,metal box, etc) that have one or more of these items inside will also be highlighted. Once the item(s) is removed, the container will no longer be highlighted. If any item(s) in this list is added to a container without said item(s), the container can be highlighted again.

A container will not be highlighted it there is only "junk" in it. It needs to have consumables (chems, food, drinks), firearms, and/or ammunition in the container.

You can also locate unopened Hollowed Out Rocks with this perk.