Bought this to replace the dead battery in my copy of Pokemon Emerald. Functions perfectly, however it is a little bit of a tight fit when closing the cartridge. Nothing too problematic, but worth mentioning. It may be possible to trim some of the holder down on the top to get it to fit better, but I'm not sure how far you'd need to go. Would still highly recommend if you're replacing your batteries.

I just installed these in 12 of my cartridges. I love them. I love that next time I need to replace the save batteries I won’t need to solder anything and I won’t need to buy any special batteries. Some carts barely fit these (carts where the battery contacts sit 45 degrees in relation to the rest of the circuitry) but even those were not difficult to install.

Full disclosure: I ordered 8 of these, received 6. Contacted HHL Support and they shipped the missing 2 VERY quickly, even adding the Route shipping protection at their own expense. Their Support Team is Outstanding!! I am semi-experienced with soldering but I was able to remove the old pins from both GB and GBA games and install these battery holders with no problems. For the GB games that use 2025 batteries, these 1616 battery holders work well, you just need to have careful placement to create a solder bridge to the prongs on the holders. Overall, great product and amazing customer service. Will definitely be doing future mods with HandHeld Legends parts!

I used them in Gameboy/Gameboy Color carts. Works great, only downside is they’re a little pricey in my opinion.

Just installed, should work but doesn't fit perfectly.

Works great for not having to re-solder batteries. However for GBA carts (or at least Pokémon Sapphire), it is just a bit to big even after filing down the plastic as much as possible since it has to sit on top of a chip. Thus the bottom of the GBA cart has a little bit of a gap, but this gap doesn't affect the cart going in or out of the console.
(photo without my finger was after filing down the plastic and one with my finger is before I did any filing)

For my GBA cart I give it a 4 of 5 but for the Game Boy and Game Boy Color carts it would be higher as they have more room.