Upgrade path

Business Glass Pane 1x2 (Trap)→ 4× Wood →Plain Wood Window Plug→ 4× Wood →Window Plug 03→ 10× Cobblestone Rocks →Cobblestone Block→ 10× Concrete Mix →Concrete Block→ 10× Forged Steel →Steel Block

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

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.