Bosch T345XF Progressor for All-purpose T-Shank Jig Saw Blade, 5-10 TPI, 5-1/4", 5-PackBosch Progressor for All purpose T Shank Jig Saw Blades offer fast, clean cuts through wood with nails, metals, particle board, and other materials. Patented progressive tooth design produces fast cuts and long life in thick and thin materials. 5 10 TPI blade means it starts at 5 TPI and progresses to 10 TPI, hence the name Progressor. T shank design for maximum grip and stability which fits 90% of all current jigsaw makes and models. 5 Pack Overall