Between 1961 and 1991, Victorinox Swiss Army knives
included a corkscrew with a slightly "looser" 4-turn spiral, and with
grooves cut into the sides.
We have seen different explanations for the grooves. Some people believe that they were purely decorative, while others feel that they help to grip the cork better, reducing the chance it will slip. It may also just be a manufacturing artifact.
We opened a few wine bottles with each type of corkscrew, and concluded that there might be a small advantage to the grooved version, but it didn't make much of a difference.
Uses: For best results, insert the corkscrew in as far as it will go (just leave yourself a little room so you can still get your fingers around the knife). Then grip the knife tightly with one hand, hold the bottle tightly with the other hand, and pull.
The corkscrew is also helpful for other tasks, including: