The Lenox Tools 20321BT314J U-Shank Bi-Metal Heavy Metal Jig Saw Blade 3-5/8-Inch x 3/8-Inch x 14 TPI - 2 Pack is designed for cutting through thick gauge metal. The 14 TPI provide you with a fast cut while giving you a relatively smooth finish. 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.