This Lenox 20814B450S is a 25-piece 4" Bimetal Jig-Saw Blade. It features 10 super-sharp TPI's that produce straight and smooth cuts on hardwoods. When talking of durability, this blade is made with bimetal construction, allowing it to twist and bend through tough wood materials without breaking. This 20814B450S is designed with a T-shank handle for superior grip, maintaining a precise cut on thick surfaces. This jig-saw blade is one of Lenox's reliable tools that can give you the convenience you need without spending a lot of money and effort.