Bosch Progressor blades offer fast, clean cuts through a wide variety of materials. Patented progressive tooth design produces fast cuts and long life in thick and thin materials. T-shank design for maximum grip and stability which fits 90% of all current jigsaw makes and models.T-shank progressor jig saw blades for fast cuts and long life10 to 24 TPI progressive tooth design for fast cuts and longer life in varied thicknesses