Omnigrid Rulers are made of durable, premium quality acrylic plastic and laser cut to provide a smooth edge that allow for easier and, deeper cutting of fabric. Designed for both left and right handed users in mind, the left and right handed numbering and angle system allow vesatile cutting with ease. Omnigrid rulers are laser cut to wihtin .002 inch accuracy and the printed graphics have a n equal tolerance. Printing on the the underside of the rulers enhances their accuracy by eliminating the distortion factor when you look through the ruler. The double line effect is printed in black and yellow which allows the user to see the grid on both dark and light fabrics.