Other things are equally suprising. First, the converter is in fact a plain piston. Initially you would think it will not hold well and that your Armani shirt (not that I own any of those!) will go to the waste bin because of some unfortunate leakage. Nothing of the sort. The converter holds well and the ink flows only through the expected exit: the excellent 14 carat nib, with an italic finish that allows you to create different thin-and-thick traces. Mind you, I own also a recently acquired second hand Conway Stewart and the Sigma nib is much less flexible. Even so, you can manage your calligraphy quite well.
I am thinking of making a table with several measurements and my own evaluation of writing comfort: I think length and weight are two essential aspects for selecting the right pen. But this will have to wait: for the moment I am busy with other things and can't devote much time to this blog neither to my little but ever growing fountain-pens collection. It will be enough for the moment to note down the main figures of this Sigma: 135 mm (total length), 115 mm (barrel length) and 139 mm (cap posted).
I purchased it at The Writing Desk for GPB 122,50 (excluding VAT and P&P). It took less than a couple of weeks top arrive and the parcel was a very well done to avoid any damage. A impeccable service throughout.