A Rubber Cricket Practice Ball

I was smitten by the ease this Cricket Practice Ball opened my AeroWatch Pocketwatch! This pocketwatch is a bit special because one can unscrew the crystal with bezel and one can also unscrew the case back without grooves. This Cricket Practice Ball is simply made for this kind of watch.
This ball is a lot less expensive then the professional opener Bergeon 5700Z which also comes with accessories (suction pads) to open screwed case backs without groves. You can see these suction pads at the bottom of the picture on this page.

Simply press the ball on the case back and turn it counter clock-wise. If the case back does not budge, apply more pressure when turning