DIC Fasteners is a Manufacturer of Spring Pins, a hollow, split dowel pin that exerts uniform outward pressure when fitted into a nut or shaft hole. These are headless cylinder-shaped tubes with a slot that runs down the middle of the pin. Spring pins are also called tension, roll, and expansion pins. These are installed in holes slightly smaller than the outside diameter of the pin. Throughout its installation, the pin is compressed along its length to create a tension that holds it tightly in the hole.