Was so excited to see these restocked. I was most interested in the .171's tiny barrel, which somehow was still smaller than i expected: under 4" it's easy to palm and pocket.
The 20mm T-nib is also pretty sharp. The line-width-variation between vertical and horizontal strokes makes me wanna snag one of these nibs for all my 15mm markers. The extended bits on the T-nib make the 10mm sides a joy to use, and as each edge being chamfered ~2.5mm (edge is cut on an angle like this: \_/) depending on the angle one writes at controls some thickness.
I like the ink itself a lot more than expected. It's a much darker black and more flowy than OTR's .060 paint markers. Give it a few pumps each go to get the nib juicy.
Lil' concerned about how quickly this marker may run out of ink? Me too, the label makes it kind hard to tell where the level's at. A typical 15mm marker is like 35ml? This marker's barrel is about a third that size, so I'm estimating you can cram ~11ml or ink in here-- which isn't too bad! Being a pump valve that should catch ya quite a few.
Might wanna Teflon tape the threads, excess ink will work its way down 'em.