OLFA® ENDURANCE™ trapezoid blades are made from high carbon tool steel (SK2) and much sharper than other similarly shaped blades. During the manufacturing process, the following factors are perfected to ensure a good balance between sharpness and long life: Hardness Sharpening Angles Tapered Dimensions Coarseness of whetstone Speed of grinding These blades are 0.6mm thick and very strong, suitable for cutting through various types of heavy-duty materials such as plasterboard, vinyl floor tiles, carpet, insulation and more.