SLATE PAVING SLABS | EBONY 800x400 | Bluesky Stone Direct - YouTube. Black slate paving slabs in 600x600 format has lovely proportions and is very easy to work with. They are of course machined on the underside to create a very consistent 20mm (nominal) depth for super fast installation, these slabs have crisp sawn sides with a gently textured riven surface.
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