Finding the right tool for the job is important, that’s why its good to know which case opening tool you need for your waterproof watch case back.
The most commonly used openers for screw off case backs are the pocket size 2 pin models and the 3 pin “JAXA” wrenches.
Click here for help choosing the right tools to open your watch back
2 pin models of openers are great for beginners to watch repair as they are economical and very easy to use. They allow you to get into some smaller spaces (opening a back without removing the band) than the larger wrenches and openers because of their pocket size. Most 2 pin case back openers have fixed pins, usually in the square shape for the most common style of notches found on case backs.
3 pin openers, commonly known as JAXA wrenches are a popular choice for watchmakers. With the ability to grab the back from 3 points you have a better grip on the case back and less chance of the wrench slipping and scratching the case. You also have better torque and will be able to open hard to open watch backs like waterproof watches.
Jaxa wrenches have removable pins that are included with the wrench when purchased so you always have the right pin for the notch. Pin styles included are: square, round, flat/polygon, and multi-notch.
Square Notches
Rounded Notches
Polygon (Flat) Sides
Multi-Notch (Grooved)
Other styles of case back opening tools for screw off backs that are popular are:
Friction 
balls are a handy tool to have at your workbench. These balls are slightly tacky and allow you to get an excellent grip on the case back.
The friction balls really do work, however they will not open every case the first time. A watch that has been used for a long time can get dirt and oil in the case threads and along with the gaskets will form into a glue that will seal the backs on certain watches that have not been opened for years. Another factor is how strong your hands are, since you do have to hold the watch in your hand. What the case ball does for you is to allow you to open most cases without having to set up another tool and run the risk of scratching the case back. Another tool to open difficult case backs for the first time will still be needed. Again, what the ball does is save time and removes the risk of damage to cases.
10 sided watch
case wrenches like these ones are great for opening polygon shaped case backs with 10 sides, such as older models by Benrus®. Fast and easy to use, simply find the right size wrench for your case and open the watch.
Horotec’s mini 
case opener provides you the same amount of torque that a press will and uses a lot less space on your workbench. It includes a removable case holder that slides out of the press so you can continue to hold the watch securely during the rest of the repair. Supplied with the same kinds of pins you would find in a JAXA wrench, this press can also use dies for opening specialty watches like Rolex® and Baume Mercier®.
How is a citizen ecodrive blue angles Skyhawk ATM case back opened up. There is no places machined in the back. Im wondering if a frection boll would work.
This watch has a caution warning on the back.
It’s brand new and it’s mine. As long as everything works im not planning on opening it. But maybe 10 years down the road if I need to replace the capacitor it would be good to know how to open it up.
Just from looking at it on Google, if it is a screw off back – you can try a case ball or one of the suction die case removers: https://www.esslinger.com/horotec-suction-die-individual/
Otherwise it could be a friction off back and would be opened with a case knife. But that is not commonly seen on water resistant watches such as this.
I have a 2000m gucci watch it’s the same watch you have pictured for making a notch for a gucci watch band guide. I cant figure out how to take the back off to replace the battery. Do I need a rubber ball to unscrew it?
This tool here is made for opening Gucci watches: https://www.esslinger.com/watch-opener-for-gucci-watches/
I want to replace the battery and gasket of my Victorinox V7-02 GMT. The back of the watch is about 1.25” in diameter and has 6 square notches. Which 3 point wrench do you suggest? Thank you.
I would say that a JAXA wrench is the best for opening. With the 3 prongs, it will get a good grip on the notches and be able to open it relatively easy. This model is a popular choice: https://www.esslinger.com/jaxa-style-watch-case-opener-wrench-for-large-watches/?_ga=2.194877741.1274254586.1598276486-1798044534.1526326902
I recently purchased the LG Openall and I am interested in using the LG Master wrench with it. I would like to see how the master wrench is connected and used before I invest in one, however, I have not been able to find a tutorial showing the tools being used together. In addition, I did read on another site that the case holder with the nylon pins that came with the Openall I purchased will not allow enough clearance for the master wrench to be used, therefore I would need to buy the original Openall movement holder in order to use the Master wrench