Conway Stewart Duro No.40 Nib. (Medium) N572 £38.00 Out of stock. Summary; Manufacturer: Conway Stewart. Designation: Duro No.40. Origin: UK. Material: 14ct Gold. Dates from (approx): 1950. Overall Length: 28mm. Writing Width: Medium. Notes: All sizes and measurements are approximate. Any replacement nib may need some adjustment when fitted to the pen. We can fit this nib as part of a service on your pen, email us for details. Postage in the UK is free on this item!