Minor correction:
This should say SuperChis, not ChisFlash. The ChisFlash carts are single-game carts that sometimes have additional hardware features like RTC support.
Flash2Advance 256Megabit image:
Intro:
Flash2Advance is an ancient Flash Cart. It came out when GBA was still the latest and greatest handheld. Main models came in 128 Megabit (16Mb) and 256 Megabit (32Mb) variants. It does not feature RTC...
Some other company designed and manufactured it, and Anbernic is just ordering them and paying to have their name put on it, like store-brand groceries.