he Parker "21" was a school-pen that followed the design of the Parker 51, but made in cheaper plastic and with an alloy 8-metal nib rather than gold. There are two distinctive designs and five different clips in the 21-line. The first design, Mark I, (1948-1951) had a larger section hole, showing more of the feed, compared to the Parker 51. Also the nib was not as tubular as the Parker 51 nib. The nib and feed was fitted tightly into the filler unit with the section screwing loosley over the top — the screw had rather a more "hollow" space in it, and because of this could contain and hold more ink. Mark I had the body imprint "Parker 21 Made in USA" and also a date imprint. Twist action pencils were also offered. In 1951 the Parker "21" Special was introduced with a stainless steel cap.

The first design cost $5 and were offered with two different clip-styles: Tapered with a "ridge" on top, no imprints and the other had an inverted Ridge-clip.

he trouble with this first design was that the ink dried on the feed too quickly if the pen was left unused for a while, but also that it sometimes too willingly released ink and created a nice blob, it also frequently leaked in the cap. So in 1952 the complete Parker 21 line was redesigned. It is important though to remember that all parts between the two Parker 21 designs are not interchangable, the nib and feed can be exchanged, the section and filler can not. The Mark II's redesigned section fitted snugly over the nib and feed — they are easily told apart since the Mark I nib and feed was attached to the filler unit when the section was unscrewed, Mark II "stuck" in the section.

The Parker 21 quickly became very popular and soon took over 60 percent of Parkers over $5 market. Also in 1952 the Parker "21" Custom was introduced with a gold filled cap, as well as the Parker "21" DeLuxe, which had a chrome cap with gold-filled trim. By 1952 the cost for a pen was $5.75 and $4.75 for a pencil, this could be compared with a Parker 51, that cost $15, a Parker 51 Special that cost $12.50 and a bottom-line (new) Parkette, which you could buy for a mere $3.50.

y 1953 The Parker 21 Super was introduced. It sported a clip that was to survive well into the 1990's on another pen, introduced in 1960, the Parker "45". This new clip was more stylized than the previous and had fewer "feathers". The first Parker 21 Super's had in fact the Ridge clip but with the addition of the Parker 45-clip and an imprint. But soon the new clip was adopted to the line. Also in 1953 a Parker "21" desk pen was offered in black.

In 1955 a Liquid Lead Parker "21" pencil was offered. The rest of the line stayed the same until 1958 when the colour Light Blue was added to the line. Also introduced this year was the Parker "21" Flighter an all steel pen that sported a red plastic gripping section. When the Parker "41" Debutante was discontinued in 1958 the white enamel cap (with a gold pattern usually referred to as the "fish scale") was instead offered on the Parker "21" range. They already had the correct "45" style clip, and fitted in style and size the Parker "21". Most Debutante "21" have been found in Dark Blue. There are also Demonstrator models known.

hile the Parker 45 was introduced in 1960 at a price of $5, it was in fact cheaper than the Parker 21 and sported a gold nib, as opposed to the octanium nib of the Parker 21. The new cartridge filling system also won the publics approval and in 1965 The Parker 21 was discontinued.

They are today very common and often excellent writers. A lot of "high class" collectors use them as their everyday pen. Due to the cheaper plastic they are however relatively easy to break, especially the sections are often found with cracks.