These refills are for the pen shown. I do not know the date of the pen as it only says it was made in England and has an accommodation clip with the Biro logo. I would estimate 1950's
It was sent to me by a customer who has a sentimental attachment to the pen which had not worked since the 50's
The new refill simply pushes into the pen and fits on the end of the section.
A choice of colours is available
Fitting Diameter 3.77mm Length132mm Tip Diameter 4.50mm
( The pen is not included! )