Doors and hatches
Business Glass Pane 1x2 (Trap)
Zombies can see through this block. The intended use is that a hidden zombie can see the player and bust out of a closet.
Upgrade path
Hit a placed block with a stone axe, claw hammer or nail gun while carrying the material of the next step: 4 hits per upgrade.
Drops when destroyed
Broken Glass× 1-3
Where to find (10 POIs)
Dr. Karen Higashi Residence (tier 5), Haven Hotel (tier 5), Higashi Pharmaceutical (tier 5), Pop-N-Pills Factory (tier 5), Holvez Rent-a-Car (tier 4), NDC Checkpoint Five (tier 4), NDC Checkpoint Three (tier 4), KLZ Radio (tier 3), Law & Order Square (tier 3), Federal Plaza.
Points of interest built with this block (any of its variants), the highest tiers first, from the game's prefab files.