This 4.5 mm thick circle-based template from Westalee features a convex and concave curve based upon the curve of a 6 inch diameter circle (including the 1/4 inch offset added by the foot). Use either side to create the same curve, which is especially useful for positioning the ruler. Easy to see etched markings run parallel to the edges and have the same 6" arc curve. Additional markings show the center and 45 degree positions. This size is very easy to manipulate when quilting on a sewing machine and fits in the hand nicely.