Tarp Fence Falling Left Green
While not as sturdy as solid concrete, iron constructions have high structural integrity, requiring fewer support pillars.
Harvest drops
Iron× 10
Taken apart with a harvesting tool (axe, pickaxe, shovel), before perks and tool bonuses.
When it collapses
Falling, it leaves 
Scrap Metal Pile (60% of the time) where it lands.
Where to find (26 POIs)
Navezgane Athletics Complex (tier 5), Butcher Pete's (tier 4), Doominium Tower (tier 4), Downtown Marketplace (tier 4), Green Hill (tier 4), Sprout & Sons Nursery (tier 4), Atlas Metal Company (tier 3), Bell Lake (tier 2), Congregation of Blind Faith (tier 2), Federal Appliance (tier 2), Sweet Sweet Honey Pot Farms (tier 2), Hook, Line, & Sinker (tier 1), Oskar's Dumpster (tier 1), Pass-N-Gas Store #01 (tier 1), The Dead Rooster (tier 1), The Roland Residence (tier 1), The Smokehouse (tier 1), Bruno's Boulevard, County Stockpile, Downtown Construction Site, Industrial Construction Site #10, Junkin, Leyline Electric Depot, Shady Dawgs, Urban Style Shops, Wasted Pass-N-Gas.
Points of interest built with this block (any of its variants), the highest tiers first, from the game's prefab files.