Nail Guard� combines an aggressive 5 TPI pattern for faster cutting, with a unique design that protects against tooth fractures. | The Fang Tip� design bites into wood on first contact for faster plunging. | Optimized tooth design providing 2X more life than our previous generation SAWZALL� blades | Tough Neck� ribs strengthen the blade tang and minimize breakage | Double relief angle reduces tooth stress for long life | Matrix II bi-metal teeth for greater durability | Thicker blade Stock for maximum durability. | 1 in. tall blade profile for straighter cuts. | Double relief angle reduces tooth stress for long life. | Matrix II bi-metal teeth for greater durability.