Category 1 represents Variante 1, the sides of the handle are made from synthetic fibre and the rivet securing the tin opener and awl has been drilled with a 2 mm hole.
Category 2 represents Variant 2, the sides of the handle are made from synthetic fibre and the rivet securing the tin opener and awl has been drilled with a 2 mm hole, which has been reinforced by a 6.2 mm diameter rosette with a thickness of 1.2 mm.
Category 3 represents Variant 3, this variant was manufactured exclusively by Wenger, the sides of the handle are "Grilon", the rivets are no longer visible except for the one securing the tin opener and awl which is still apparent. The 2 mm hole, reinforced by a 6.2 mm diameter rosette with a thickness of 1.2 mm is still present.
The "1951 Models" with "Grilon" handles were made from 1957 to 1964, well after the commissioning of the "1961 Models".
Please note : The colour of the "Grilon" handle can vary significantly, ranging from bright, shiny red to dark red-brown almost matt, making it difficult to identify the variant 3 at first glance. It is easy to confuse variant 3 and variant 2.