The Large Round Crenellations Pack is part of the Castle Builder System. It is made of "Dwarvenite". This item was initially available as an add-on to a pledge level during the Castle Builder System Kickstarter. The item comes in both painted and unpainted versions.
The Large Round Crenellations Pack comes with these 9 pieces:
(3) Large Curved Crenellation
(1) Large Curved Crenellation w Trapdoor
(1) Reinforced Lattice Trapdoor
(2) 6in Tower Half Roof Platform
(1) 6in Tower Roof Platform
(1) 6in Tower 3/4 Roof Platform