Great for home-brew and backups alike. No more batteries!
For Flash Cartridge ROM 2MB @ FRAM 32KB for GameBoy
This was my very first foray into the world of flash carts, repro carts, home-brew, bootlegs, et cetera, so I wasn't sure what to expect. So I initially bought just one of these flash carts to try it out, and I wanted to use it to make my own repro cart for Tobu Tobu Girl (which is a wonderful home-brew game for Game Boy, by the way, everyone should check it out). I also got J.Rodrigo's cart flasher/dumper to help with that, and I would definitely recommend that too if you don't already have one.
Anyway, back to the flash cart. I got the first one and I was so impressed with the very professional build quality of the actual PCB inside. The soldering on all the connections is clean. The contact pins are perfectly aligned and don't feel like they'll come loose. The cool black color is also a very nice touch. One of the nicest things about these carts is that they don't use batteries, and instead they use non-volatile flash storage for game saves. That means you effectively never have to worry about losing your save files (barring things like user error or natural disasters, of course).
But the very best thing about these carts is how easy they are to use. The memory bank controller that J.Rodrigo uses is very versatile and reliable. These flash carts will take any ROM you throw at them with ease. I finished making my Tobu Tobu Girl repro cart, and I was so blown away by this combination of a high quality product that is also super easy to use, that I instantly bought four more of these flash carts. I'm using one of them for the fan translation ROM hack of For the Frog the Bell Tolls [Kaeru no Tame ni Kane wa Naru]. (Which I obtained by patching a legit backup of an imported copy of the game. Remember, downloading ROMs from the Internet is not only illegal but also risky for malware. Always use a cart dumper device.) The rest of the flash carts I'm using for backups of all three of my Gen I Pokémon games (Red, Blue, Yellow) and their save files so I don't have to worry about batteries any more.
I don't want to clean out J.Rodrigo's supply of these flash carts, so I'll refrain from buying any more for a while so other people can buy them too. But eventually I might maybe like to make backups of all my other battery-based Game Boy games using these battery-less flash carts. They're that good.
Anyway, all that to say, this is a very high quality product and I am very impressed and very happy. Highly recommended for anyone looking to make their own repro carts for home-brew games, or to make everlasting battery-less backups of original Game Boy games. Thanks for a wonderful product!
NOTE: Because Pokémon Gen II (Gold, Silver, Crystal) uses a real-time clock that requires a power source (i.e. a battery) to function properly to keep time even when the game is off and not being played, these carts are not ideal for backups of those games, unless you're willing to give up the real-time clock function. So for those three games I'll still be changing batteries every seven years or so. Ah well, c'est la vie.
EDIT: I would like to add a small update after a few days of using these carts. All is well! Since I have been using these carts extensively, I want to address some of the complaints I saw in a previous review left in February 2017.
One of the complaints that reviewer had was that these carts were not very compatible with Pokémon games and produced graphical issues when played. I cannot speak for versions of the games released in other regions, but for the North American releases of Pokémon Red, Blue, and Yellow, these carts are working flawlessly for me.
Another criticism had to do with the thickness of the actual PCB inside the cart, where the previous reviewer said the boards in these flash carts were about twice as thick as OEM Game Boy cart PCBs. I can definitively say this is no longer the case, as all the flash carts I received have boards that are very close to exactly the same thickness as OEM boards; maybe 0.1 mm thicker, if anything.
It would seem that J.Rodrigo has thoroughly refined and improved his process since that review was left in 2017. So while the complaints may have been valid at the time, they should not concern prospective buyers any longer. Happy flashing!