Krone are an American manufacturer of high end pens. This is the Krone Clarity, a demonstrator pen designed to show the inner workings of the pen. This is a top quality pen, fitted with platinum trim and sporting a huge 18ct gold nib.
The pen is in excellent used condition with no scratches, chips or cracks to the acrylic.
The nib is marked as a Medium but seems to me to be more of Medium / Broad. Whatever you want to call it it is still very smooth and easy to write with.
This is a large, prestigious pen with a great deal of presence. The wonderful nib makes it that bit more desirable!