Victorinox developed the No. 70 U model in the 1920s. It is identical in design and construction to the Model No. 70 except that the small cutting blade has been replaced with a watch case opener. However, the addition "U" can be confusing, as it also stands for a pocket knife with a bail or ring.
Switzerland has a long tradition in watchmaking, which was certainly one reason for building this special tool into a pocket knife. In the course of development, there were different variants of watch case openers. This was used to open the back of watches to expose the movement. This required a watch case opener which was not sharpened but rounded so as not to cause any damage.
Cellidor scale material was originally used. Later this was mainly replaced by aluminium. The scales were almost always provided with the logo or lettering of a watch company, which used these pocket knives for advertising purposes, but also for use by their employees.
Model No. 70 U had a large cutting blade and a watch case opener. There were no add-on options for this model.
Large blade: 2.4 mm (later on Alox models: 2.0 mm); Scale opener: 1.2 mm (Later 1.0 mm)
A central rivet fixes the symmetrical back spring. The large cutting blade moves on the head rivet, while the small cutting blade or the watch case opener and the intermediate layer are fixed on the base rivet.
In the beginning Cellidor black was the main scale material used, later aluminum was the main choice.
Liners, interlayer, rivets
The liners and the intermediate layers were made of brass. The rivets were also brass, except for the models with aluminum scales, which used nickel silver rivets.
Trade Names: Watch Case Opener, Watch Case Opener, Watch Case Opener