The two "frequencies" on the blade of this Shun Classic Dual Density Utility Knife (shown here above a classic Santoku) are created by the teeth and the undulating cut in the bottom edge of the blade. Together, they create a a tool that can be used to slice through the softest tomatoes and the toughest bread crusts alike. It's handcrafted with the same features of Shun Knives: a beautiful PakkaWood handle and damaskeened ground steel blade. Given its versatility, size and craftsmanship, it's a great buy at $99. Mind your fingers.