We find the .7mm lead to be the perfect compromise able to create fine lines without the delicate breakablility of .5mm lead

This model appears to be an update to Rotring's legendary 600 product line.

I prefer the thicker, darker lines of the .7mm but when very detailed drawings are needed I grab for the .5mm

Use the .7 if you like thicker lines and write bigger.

It has a nice weight to it which makes it easier to write for long period because I don't have to press as hard to get solid, even lines and writes very precisely

I prefer the thicker, darker lines of the .7mm but when very detailed drawings are needed I grab for the .5mm

I find the .7 allows you to write longer,while still maintaining a fine line.