Part of the Park Sentry Square system: Corners measure 1m tall with a thickness of 55mm and extend 85mm from the corner on each side. Corners ship four/carton and include interlocking keys. To cover a square column up to 610x610mm, order 1 carton of corners, 1 carton of planks, and a set of reflective 4m straps. For larger columns, add more planks.