When is a wrench not a wrench?

So it turns out not only was the wrench not needed, but if it was, I got the wrong kind. All of the watches I've dealt with are opened by prying off the backing. This is how I've destroyed a number of screw drivers, so I thought a dedicated tool might do a better job. Turns out I was wrong. This wrench is for "jaxa" style watches which have little grooves on the backing which line up with the wrench. The back is then unscrewed.

Whoops. There goes $6...

Edit, actually, someone on my hall has a slide rule watch which wasn't slide ruling very smoothly. Using my new wrench, I was able to take the backing off her watch and apply some lubricant to the slide rule gear. $6 well spent.