The Lenox Tools 20328BT480J U-Shank Bi-Metal Wood Cutting Jig Saw Blade 4-Inch x 3/8-Inch x 10 TPI - 2 Pack is designed for fast wood cutting and works with nail embedded wood as well. The 6 TPI allow you to cut extremely quickly, while the sharpness of the high speed steel and the precision ground teeth give you a smooth cut. The teeth are ground to precision sharpness for straight cuts. The Bi-Metal Construction makes the blade more durable and flexible than a traditional Carbon Steel Blade. These blades are made with a Universal Shank that fits most Jig Saws.