Case openers are used to open watch cases. They make it easier to flip open the watch case and prevent scratches or marks from forming. Ideal for anyone who wants to change the battery or fix the watch movement. Different case opener types include knives or wrenches. Knives are used for snap on cases. The case opener will carefull snap off the case backing. Wrenches are use for screw-on back-cases, which will help unscrew the case backing.