This is a simple tool for removing the acrylic crystal from a one piece case design. The claws grip on the outside rim of the crystal compressing it until it can be raised out of the case, giving access to the movement. The tool can also be used to install the same crystal back into the case. Squeeze too hard and the crystal may crack. Don’t get the tool properly aligned on the crystal it may slip off leaving a nasty scratch. It does do the job however. An alternative method is a pump which pops the crystal off with pressurized air — never tried that before.