This is a good example of an early Swan Self Filling Fountain Pen, this is the SF230 which was made in the UK and dates from around 1930.
The pen is made from Black hard rubber which has faded to a dark brown on the barrel. The imprint on the barrel is faint but still legible and the pen is in excellent condition overall with some minor plating wear to the barrel bands, lever and clip.
The No.2 Medium nib writes smoothly and has a lovely light flex to it.
The pen has been fully serviced and is ready to write.