Fiskars 8.5x8.5 Square Acrylic Ruler (187200-1001) (187200-1000) For dedicated quilters, this is the essential ruler for squaring and centering Center 45-degree bias line is clearly marked Durable 3mm thick clear acrylic Highlighted 1/2-inch seam allowance measurement Model numbers 187200-1002 and 187200-1001 is exactly the same item