The Ultem look is beautiful. The bolt action works exactly as expected. Feels very well made. Pen’s a bit on heavy side, but doesn’t take away from the great writing experience.

I’m very satisfied with my Bastion Ultem bolt action pen! it has a very smooth operation, and it definitely gets looks!

I purchased an Ultem and the G-10 at the same time, I was looking foreword to the G-10, but only got the Ultem because it looked interesting. After a few days, I think this Ultem is my favorite Bastion pen. Maybe its the demonstrator aspect of it of it, or how smooth the action is, or how lightweight it is. Whatever it is, I REALLY like this pen! Now I'm hoping Bastion will make the Ultem in different colors?

Bastion pens are the epitome of machined pens. The metal pens feel solid and robust, the machining is CNC-precise, the bolt action actuator to extend and retract the writing tip is so smooth, simple and robust that you will NEVER wear it out with regular use. Even with compulsive clicking of the actuator, your thumb will fail before the actuator. The drawback to the Bastion metal pens? Mass! The Stainless Steel, Brass, Copper, and to a lesser degree, Titanium and Zirconium pens are made from solid metal, the walls of the pen body are probably 10x thicker than a Parker Jotter. The Aluminum pen is built the same way, but due to aluminum’s lightness, there is less mass of metal in your fingers. I say “mass” instead of “weight”, because you also need to consider Newton’s 1st Law of Motion (Inertia): “An object at rest…”. Unless you’re only drawing straight lines, infinitely long, your fingers, hand, wrist and arm need to overcome the pen’s inertia when writing. Not everyone does wrist curls at the gym, even though they should, so prolonged writing with these massive pens may cause muscle fatigue sooner than a less massive pen. Bastion tried to mitigate this by producing “Slim” pens; less girth, somewhat less mass, same build quality.
And thus the decision was made to use “engineered plastic” to create a pen that is almost as robust as a metal pen, but with significantly less mass. Delrin is one such plastic; they make gears for car engines out of that. Polyetherimide (PEI, brand name Ultem) is nearly as tough, but even lighter, and has been used in the aviation and space industry for decades, because it is very deformation and impact resistant, even at high temperatures, and is nearly impervious to most chemicals (except ammonia, don’t use Windex to clean it!). And it’s translucent to transparent, based on final polish of the product.
The use of Ultem makes it possible for Bastion to make a pen that is virtually indestructible (in normal use, no ammonia!), but with less mass than its lightest metal pen!
A word about the mass: the pen is “back weighted”. Some people think that pens should be perfectly balanced, but I disagree. When writing, it’s the tip that makes most of the movements; the more massive backend stays “anchored” on the web of your hand between index finger and thumb. There’s a metal tubular slider that “grabs” the back of the Parker G2 style refill to ensure the refill stays centered in the pen barrel during the tip’s in & out travel.
The pen writes very well. There are no special anti-slip grooves, knurling, or rubber coatings, but even though it’s plastic, the surface has just enough texture to keep your fingers from slipping, just like the metal pens. It’s just as girthy as the standard metal pens, as well. It comes with a black gel ink refill installed, and a spare refill. Bastion will sell you identical looking refills filled with oil based ballpoint ink, but the OEM refills work just fine, good color saturation, and very smooth even ink flow. Primarily for aesthetic purposes, I put an OHTO Needlepoint refill (PS-107NP) in my pen, because the refills are clear plastic, so I can see the remaining ink level right through the pen.
I recommend this pen to anyone who wants Bastion quality, reliability and simplicity in a MUCH less massive format. And Ultem looks cool.

I like it being transparent. Other than that it is the same as the other Bastion bolt action pens.
If I knew you were coming out with a blue one I probably would not have bought the yellow one.