SO much easier to work with that Rapidographs. the pens haven't clogged after nearly constant use and two refills since last week when I got them. The ink flow starts easily and it stays constant (for me) until there is no ink left . I did get a couple of items I don't know what to do with I am guessing they are attachments for a compass. The only complaint I have is the instructions are so small I just gave up and looked for an online tutorial . These remind me of the pens I used in art school. They just seem more like a work horse than the too delicate and easily damaged Rapidograph. I'm not saying you can treat them like a ball point pen, but I just got a Rapidograph that broke after the second or third use. I had to constantly shake it to get ink down into the tip and it often splattered ink because of that . It was also much messier to refill it. My point being, if you are on the fence about what kind of pen to get I highly recommend Rotring . Also good communication from seller -checking up on my satisfaction .

Great pen. Exactly what I needed. Replaced my rapidograph of the same brand and size. That one had a bent tip and constantly beading up ink on the tip. I like the isograph better because you can put as much ink as you want.

The pen worked just okay for the first couple of uses but recently it started leaking from the tip and the pen stopped working all together. We followed instructions for cleaning the entire pen which did not work.

Update: Upon further disassembly of the pen I found the super thin piece of wire that is supposed to run inside the tip was completely bent and curled. I tried to gently straighten it and it fell off. Not acceptable for such an expensive pen. My guess is that the pen was not correctly assembled at the factory so when I shook the pen (as designed) the wire was just getting beat up inside the pen rather than sliding in and out of the tip.

This pen is amazing.
It's precise and accurate, easy to refill and very sturdy.
The only thing is that it can bleed a bit, and doesn't dry fast enough for me.
Regardless, it's an excellent purchase and I will use them often.

Rotring pens are AMAZING. I'm actually replacing all of my Koh-i-noor technical pens to Rotring after my first purchase of a .10 mm a few months ago. The ink flow is SO smooth, no "skips" as you're drawing, and you don't have to fight it after you get the initial ink flow (which, getting the ink flowing is super simple too!). These pens are amazing, and are a must have for any illustrator, artist, graphic designer, etc. who heavily uses technical pens in their work. I also absolutely love the case they come in, and the fact that the "lid" has several templates on it! The pencil has a nice weight to it as well, and has a comfy grip for sketching.