On white dual edge blades for heavy-duty Circle cutter (c-2500p, c-3000gp) and large Circle cutter (cl-100p). this extra durable double-sided blade is thicker than the standard Circle cutter blades. These heavy-duty blades are 1mm thick for heavy-duty jobs. 1 refill blade is packed in a protective plastic container with a convenient hanging hole. These professional blades are made of high quality carbon tool steel and produced through multiple stages of precise process to obtain the ultimate sharpness and optimum edge-retention. Made in Japan.