The pens from the Pro-Grip Brites series by D' Andrea USA are made from Delrin and are designed to solve the slipping problem. Each pen is crafted from the most popular material, delrin/acetate, and carefully manufactured to mimic the authentic look of a turtle shell. These pens are similar to the traditional 351 pens, featuring sharper tips, offering a different way of expression without compromising the familiar 351 size feel. They are available in various thicknesses and are made in the USA.