Back into use today is my very expensive TWSBI knockoff aka the M805 Clear Demonstrator SE. This pen worries more than all my other pens put together. I would hate to stain it beautiful crystal clear acrylic.
Into use today comes a very old M800 18K medium nib, the telltale marks to back up this statement are the two chicks and the stamped symbol to the right of M nib size imprint. This nib writes OK - a medium nib is seldom exciting.
This ink was last in use in September 2016, wow how time flies. Black is the most boring ink colour of them all, the most you can expect is minimal shading. On the plus side, there is nothing that says business like black ink on a white page.