Blue Iron Door Double
Press & hold Activate to lock it or set a combination. Upgrade & repair with a construction tool using the secondary action.
Upgrade path
Hit a placed block with a stone axe, claw hammer or nail gun while carrying the material of the next step: 6 hits per upgrade.
Crafting
Craft at Backpack · makes 1
Crafted as Iron Double Door: pick this one of its variants when you place it.
Forged Iron× 10
Harvest drops
Iron× 4-10
Taken apart with a harvesting tool (axe, pickaxe, shovel), before perks and tool bonuses.
Drops when destroyed
- Iron× 10
When it collapses
Falling, it leaves 
Scrap Metal Pile (75% of the time) where it lands.
Where to find (5 POIs)
Champions Coliseum (tier 5), Correa Rockworx (tier 5), ChemTech Distribution Center (tier 4), Animal Hospital (tier 2), Hybrid Energy Substation #2 (tier 2).
Points of interest built with this block (any of its variants), the highest tiers first, from the game's prefab files.