Set R consists of two triangles (Peaky and Spike) with which you can make 5 inch units for 10 and 15 inch blocks. This set is compatible with set Q. The templates are made of the same acrylic material as quilt rulers, so they can be used with a rotary cutter. First, strips are cut of the right width, and then the templates are positioned on the strips, to make the second cut. Each template has double blunt corners for perfect alignment. The blocks go together past, easy and perfect!