Vaulted Diagonal Wall Pack is part of the Dungeon of Doom series. It is made of "Dwarvenite" and includes some metal and magnetized parts. This item was initially available as an add-on pack during the Dungeon of Doom Kickstarter. The item comes in both painted and unpainted versions.
Vaulted Diagonal Pack comes with these 26 pieces:
(14) Vaulted Diagonal Wall
(2) Vaulted Diagonal Wall w/ Door
(2) -- Ancient Door
(8) Diagonal Half-Floor