The natural cleft is not rough to touch and very comfortable under bare foot. It is a dense stone, holding heat particularly, and is available in black with a wide variety of sizes.
400x200x10 (+/-2mm)
300x300x10 (+/-2mm)
400x400x10 (+/-2mm)
600x300x10 (+/-2mm)
600x400x10 (+/-2mm)
600x600x10 (+/-2mm)
900x600x10 (+/-2mm)
1200x600x10 (+/-2mm)
900x900x10 (+/-2mm)
1200x900x10 (+/-2mm)