Prym Universal Ruler Inch Scale 12.5 x 12.5 inch OmnigridPrym Universal Ruler Inch Scale 12. 5 x 12. 5 inch Omnigrid Whether on the cutting table or the sewing machine the Omnigrid universal rulers from Prym are indispensable companions for patchwork dressmaking and tailoring or for graphic work. The yellow and black grid markings with an inch scale make it possible to mark accurately on both dark and light fabrics. The scratch resistant laser print on the underside of the ruler prevents visual distortion.