The Pelikan's first school fountain pen model 120 was characterized by a partially transparent non-striped green barrel. The model  was discontinued on May 23, 1965.

 

Model 120 revived for a short period of time. The piston filler MK10 with a steel nib and green barrel was sold as 120 from 1967 to 1969 for the export market (Pelikan-collectibles)⁽¹⁾.

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In Japan, the classic style piston filler 400NN continued to enjoy great popularity even after it was discontinued in 1965. In response to strong demand from Japanese retailers, Pelikan decided to reissue 400NN for the Japanese market. Model 120 was to be revived accordingly⁽²⁾. However, after stopped their production in 1965, Pelikan abandoned its manufacturing facilities and concentrated on "the Pelikano business" (Pelikan: Ein Unternehmen schreibt Geschichte). So, Pelikan had to outsource their production to Merz & Krell (Pelikan: Ein Unternehmen schreibt Geschichte). 120 (and 400NN) was finally produced by Merz & Krell in 1973⁽³⁾. There were three types of barrels: green, black, and green-striped (Pelikan-collectibles).

Merz & Krell version had many subtle to notable differences from the original 120 (万年筆おやじの備忘録)⁽⁴⁾.

• The cap top had no Pelikan logo (Fig.3-1).

• The cap top was smaller in size (Fig.3-3).

• The clip had different size (wider and longer), design (Pelican head), and different engraving (M & K: (none) vs. original: m) (Fig.3-3).

• The clip had a thinner ring (Fig.3-3).

• The cap tube became longer (Fig.1-4).

• The cap tube ring was beveled (original: straight) (Fig.3-3).

• The cap tube "Pelikan 120" logo had a different character style (Fig.3-2). 

• The collar had a different construction and a thread (incompatible with the section of original 120, and vice versa) (Fig.2-3).

• The feed had different construction and diameter (M & K: 5 mm vs. original: 5.5 mm)(incompatible with the collar of original 120, and vice versa) (Fig.2-2, 2-3).

• The nib had a different Pelikan logo (M & K: one chick vs. original: two chicks) (Fig.2-1).

• The nib had no positioning hole at its base (Fig.2-1).

• The section had a different thread (incompatible with the cap tube of original 120, and vice versa) (Fig.1-3).

• The section had a different edge shape  (Fig.1-3).

• ​The turning knob was larger in diameter (as a result, there was no step between the turning knob and the barrel)(Fig.1-4).

• The barrel and the turning knob was longer. The overall length was 7mm longer for M & K (Fig.1-4).

• The overall look is more streamlined (Fig.1-4).

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In 1977, the Merz & Krell version of 120 was discontinued.

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In 2016, 120 again revived as M120 (Pelikan-collectibles) (Fig.4).

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Note:⁽¹⁾"The cap is also amended, lacking the Pelikan logo on the derby and having a beveled band similar to that seen on the MK10, for which this pen might well have been meant as a replacement… although the MK10 had a more literal descendant in the 1970s under the name of M480" (Ravens March Fountain Pens). MK10 with a steel nib and green barrel revived as "M480" in 1973 (Pelikan-collectibles). 

⁽²⁾Nostalgia for old fountain pens in the West also seems to have contributed to the revival (Ravens March Fountain Pens).

⁽³⁾Presumably, Pelikan 120 (Merz & Krell) with a 14 carat gold nib was made for the US market (Fountain Pen Network).

⁽⁴⁾In 400NN Merz & Krell, the piston mechanism was screw-in fitted to the barrel and the piston seal was integrated with the piston rod; the 120NN Merz & Krell probably had a similar construction (not confirmed because it could not be disassembled).