Rotring Core Rollerball

This is a pen which may look a bit strange, both in shape and considering the colours it's available in. I've got one light green and grey and one dark grey and orange. The impression is reinforced by the names the colour combinations are given.

However, while design may sometimes be a goal in itself, in this case it's not regarding the shape, as this is a very practical and functional pen. Nevermind that the different models also have different patterns of partially nonsense printing on them, when you hold and write with the pen you notice it's very much made to be used.

The overall design is well thought out. The holes in the barrel aren't just for show and checking the ink level (which considering most rollerball refills available here aren't transparent doesn't do much for me), together with the patterning on the cap they aid in mounting and removing the cap, whether you use one or two hands.

Both capped and uncapped it's comfortable to write with. Its cap is pretty large diameter, but apart from that it sits well in pockets.

I don't use mine with just rollerball refills. G-2 style gel refills fit in it, as do the very smooth ballpoint refill, the Pilot XB (1.6 mm), which fits after just trimming a bit at the rear. (Since this one clots a bit when you carry it in a retractable pen, I think it's a good thing to carry it tip up.)

I often carry it in a [break away] cord around my neck. Very suitable for that.

Basic data

Mass                     16 g + 14 g cap
Tip-centre of mass       75 mm uncapped
                        105 mm capped
Total length            144 mm
Diameter ~60 mm from tip 14-14.2 mm
Protusion over clip       4 mm