Replacement 12.5mm snap-off blades for the OLFA® CS-5 Combination Keyhole Saw & 12.5mm Cutter. OLFA® ENDURANCE™ blades are made from high carbon tool steel (SK-2) and sharper than most other snap-off blades in the world. 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 Each blade has 9 cutting segments, so this pack of 10 blades will give you 90 new edges, lasting a very long time.