The Lenox Tools 20755CTS406J U-Shank High Carbon Steel Wood Cutting Jig Saw Blade 4-Inch x 3/8-Inch x 6 TPI - 2 Pack is designed for fast rough cuts in wood. The 6 TPI allow you to cut extremely quickly, while the sharpness of the carbon steel and the precision ground teeth give you a smooth cut. The teeth are ground to precision sharpness for straight cuts. These blades are made with a Universal Shank that fits most Jig Saws.