LENOX Tools 1991567 T-Shank medium metal cutting jig saw blade, 3 5/8-inch X 3/8-inch 18 TPI, 25-pack provides users with improved blade durability and long life in medium metal. Power blast technology strengthens the blade to reduce breaks and increase durability. Patented T2 technology provides fast, efficient cutting in a range of metal cutting applications. Bi-metal technology flexes to resist breaking and extend blade life.