The Ti Pocket Pro is the only pen that can seamlessly telescope to accommodate 80+ different refills without any guesswork, gaps, hacks, modifications, spacers, or tip-wiggle.
The entire pen is made from titanium (no plastic parts) with exception of the o-rings.
It's seemingly effortless ability to transform in length to perfectly fit both parker-style ballpoint refills and standard rollerball refills without any visible gaps or hacks makes it a pen without peers.