These concave blades are made from sheffield steel to the highest quality. They are single sided and are used for the sharp point to score. When cutting thick vinyl tiles the fitters score then snap the tile. These blades are ideal for this type of installation. The blade has two knotches and fits all the standard utility knives in the trade. Wrapped in 5’s into boxes of 100. Fits the Delphin knife, Stanley knife, shark knife and all standard utility knives.