The Parker Duofold Slimfold was first introduced in 1962 as part of the Duofold Aerometric range. The range consisted of the the Slimfold with the No.5 nib, the Junior with the larger No.10 nib, the standard Duofold and the Demi with the No.25 nib, the Senior with the No.35 nib and, finally, the prestigious Maxima, fitted with the huge No.50 nib. The range was produced right through to the 1970's and they were extremely popular because of their reliability and quality.
This particular pen is a Duofold Slimfold dating from around 1972. It is the last of the Slimfold range and the design is very similar to a Parker 45 (It uses the same nib unit) apart from the cap is screwed on rather than the push fit on the 45.
The pen is finished in Burgundy with chrome filled trim to the clip and cap ring. It is fitted with a super smooth Medium nib which writes nicely. The pen uses Parker cartridges or a converter can be fitted so the pen can be used with bottled ink.
The Slimfold Mk4 is a rare beast, in fact this is the only one I have seen, they were not made for very long before the range was discontinued. The pen is in excellent condition with very minor marks and scratches commensurate with use. The imprint on the barrel is clear.