This is the Wills SSMP228 HO/OO Random Stone (4)

These sheets are invaluable for scratchbuilding, saving many hours of repetitive work creating the various surface patterns and textures. They are the same as those used in the Craftsman kits to make extension work easier. Each pack contains 4 sheets 130mm x 75mm of injection moulded styrene approximately 2mm thick, making them rigid enough to be self supporting.