Whether you need to replace a component in the watch or you just want to know how it ticks, you'll need to pop off the back of a watch to access its contents. Avoid doing this if you don't know what you're doing, because you may damage the watch. But if you need to do it, you can use a few techniques to get the back off quickly and easily, depending on the type of watch you have.
Use a case opener tool for a watch with a screw-off watch back. Line up the tool's prongs in the case back with the tool's adjustable wheel. While holding the case back, twist the tool counterclockwise to pop off the back.
Find a slight cutout or indentation along the edge of the back of the watch with a pressure-fit snap-off case back, which may require a magnifying glass or loupe. Slide a watch case opener blade into the indentation and make a slight clockwise twist while pressing the blade downward to pop off the back.
Use a set of watch repair screwdrivers to open a watch back with four screws. Lay the watch face down on a cloth and test a few screwdrivers on the screws until you find the right size. Turn the screwdriver counterclockwise to remove the screws, which will allow you to open the back.