This knife is the Soldatenmesser Model 51 with red Grilon scales (Grilonschalen). According to records, Wenger started making knives with Grilon scales in about 1951. These red scaled knives were made from 1951 to 1972 or later. These knives are not manufactured by Elsener. In 1961, Wenger also brought in the new red-anodized aluminum scaled knives, but as with most model changes, there was a transitional period. In this transition period, the remaining model 51’s were dismantled, but you can still find brown fiber grips made until 1964 or later.
The Grilon scaled knives are the same size as brown fiber scaled knives. The blade and other tools appear to be the same as the original length. The easiest way to spot these transition knives is to look for the red color and lack of pins in the scales.
Grilon Knife handles that are made from genuine Grilon (Swiss Nylon Quality) are unbreakable, heatproof to 150 degrees Celsius, do not absorb any grease or dirt and have a non-slip surface.