On this page, you can download the latest firmware for the R4 3DS DUAL CORE cards. This firmware is made specifically for the cards you see below and it is not compatible with other cards or clone/fake R4 3DS Dual Core cards that have the .hk or the .com.cn website addresses on them. You will simply see a message that states that it is not a real card if the wrong firmware is put on the R4 3DS.
The very same R4 3DS Dual Core Firmware works on all of the Dual Core cards from 2016 onwards. If you have a card with the 2016 Banner, 2017 Banner, 2018 Banner, 2019 banner or this newest version, this is the firmware you need to use so that you card can work without issues.
Please choose the language version of the kernel for your card. The firmware is the same for each language and the only difference is having it in your local language. There are some exceptions and some parts of the firmware in a different language than English may still have some parts that are actually in English.