A great starter ruler, this 4.5 mm thick circle-based template from Westalee features a convex curve based upon the curve of aÂ 12Â inch diameter circle and a straight edge on the other side. Length of straight edge is 6-7/8 inches long. Easy to see etched markings run along either side at 1/4 inch spacings. Several half inch and inch etched lines run across the template for additional help in placement. This ruler is the same ruler that comes with the ruler foot kit from Westalee and has the same curved edge as the 12" Arc, with a smaller length.