The Lenox Tools 20337BT456J U-Shank Bi-Metal Fast Cut Jig Saw Blade 4-Inch x 5/16-Inch x 6 TPI - 2 Pack gives users the ability to make very fast cuts. The 6 TPI allow you to cut extremely quickly, while the sharpness of the carbon steel and the precision ground teeth give you a nice clean finish. The teeth are ground to precision sharpness for straight cuts. These blades are made with a Universal Shank that fits most Jig Saws.