LENOX Tools 1991569 U-Shank medium metal cutting jig saw blade, 3 5/8-inch X 3/8-inch 18 TPI, 3-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.