The OmniEdge ruler is idea for cutting straight and bias pieces with a rotary cutter or a straight-edge blade. The ruler has a lip that catches on your cutting mat to prevent slipping during cutting; the ruler's lip, or channel, is easily removed to position the ruler as desired. Details:Clear3" x 18"1/8" lip prevents slippingLip can be removed45 and 60 degree angle linesHighlighted numbers and outer edges reduce cutting errorsLeft- and right-hand numbering and angle systemDouble-sight lines visible on light and dark fabricsAcrylicFor use with rotary cutter or straight-edge blade