This is just the bolt that you push on to advance and retract the mechanism for the Slider and Glider Pens and the Pencil. It is not the internal part, only the bolt that advances and retracts the mechanism.
Titanium Damascus is different alloys of titanium that are forged together and twisted to create a cool pattern and after they are machined we heat them to bring out the pattern. Every bolt looks a little different. These are unique pieces and every one has variation from the next. Take a look at the photo that shows a few examples before selecting this option.
These parts are threaded, so unscrewing the old one and screwing the new one in tightly is required. We use Knipex smooth jaw pliers to install these so they won't come out very easily. Be careful if you are removing your bolt as it is easy to scratch the pens. Most pliers are made from hardened steel and will scratch even our toughest titanium, zirconium, and stainless steel pens.