Castle Mosaics Pewter is a 12" x 11" mosaic from Centura's Castle Mosaics range. Centura rates this one for walls, not floors, which puts it in backsplash, surround and feature wall territory. Boxes hold 18 pieces and cover 16.66 sq ft, or 0.9256 sq ft a piece. Being mesh-mounted, the sheet holds its spacing as it goes up and trims down to meet a corner or niche.