Double length GPO specification curly handset cords.
These are perfect for GPO wall telephones 711 and 741.
These are also perfect for the desk models as well if you find the standard length too short.
I have had these specially made for me due to being constantly asked for them.
They are made from 6 meter length cordage and so should pull out to around 5 meters.
These are identical in specification to the standard length cords.
See an example of a 741 GPO wall telephone fitted with one.