LENOX Tools 1991614 T-Shank plastic cutting jig saw blade, 4-inch x 5/16-inch 12 TPI, 3-pack provides users with improved blade durability and clean, smooth cuts in plastic. Power blast technology® strengthens the blade to reduce breaks and increase durability. Precision ground teeth with optimized tooth angles provide a clean finish. Bi-metal technology flexes to resist breaking and extend blade life.