It's important to learn how to properly open the back of a Seiko watch. This knowledge is especially useful if your battery is dead and you want to find out what battery you need to replace it with. Learn how to identify which watch back your watch has, how to remove it and how to locate the battery and battery number.
There are three types of watch backs: snap on, screw on using screws and screw on using a press. This tutorial will be dealing with a snap on. Keep in mind that if you take your watch to a watch repair shop, they will unscrew the back for free. It is easy to take the back off of a snap back or a screw-on back using screws. However, if your watch has little notches all along the edges, it has a screw-on back that needs a special press to remove it. There are ways to unscrew this back at home, but you could injure yourself in the process. Identifying a snap back is easy. If the back of your watch does not have visible screws or notches, it is a snap-on back.
Look for a small lip or indentation on the edge of the back. You can find the lip up or around where the watch band is.
Use either a dull knife (emphasis on dull) or a screwdriver. Put the flat end of your tool inside the lip and try to pry it off. Hold the back of the watch down with one hand while prying off the side where the lip is with the other hand.
Check the battery number once the back is off. The battery number is on the side that is sticking out when you open it. Once you know the battery number, you can go to any watch repair shop and get a new battery.