The Forster Products 011521 is a high-quality Co-Ax Primer Seater. This essential tool specifically works by its tube bottoming against the flat surface of the primer housing. To ensure proper functioning, the bottom of the tube requires a slight funneling in.Constructed from a lightweight, soft material, you can easily modify the tube to fit your needs. You can bend, file, or trim it using a penknife. Plus, the tube features a slot for visual inspection. With this practical feature, you can conveniently check for any reversed primers.