The Parker 21 Mk.1 was only made from 1948 to 1951 when the section and cap design were modified for the Mk. 2 version, a more practical pen than the original.  In 1956 the Parker 21 Super, this pen, was introduced. 

The 21 was discontinued in 1965, probably because the Parker 45 was now a competitor.  

This is a particularly fine example. Finished in Green, with a stainless steel cap and the redesigned 'arrow' clip.  The body and hood have an excellent surface with a very good shine and no visible scrartches or other blemishes.  The cap, which is engraved with '21', is also in good condition.

The Green colour, the least common Parker 21 colours by far, is strikingly attractive and quite collectable. 

The filling system, a modified 'Aerometric', has a clear ink sac and works well.  The Parker 'Octanium' nib writes with a beautifully smooth and consistent medium, line, a very 'easy' writer.  

The Parker 21 is an extremely good choice as an unusual and dependable every day writer and is often favoured rather than the much more expensive Parker 51 to which it bears a close, if superficial resemblance.  It is an excellent pen in its own right.