Crystal Clear was a .bps patch file that was initially developed in 2017 by ShockSlayer.
It is currently only available via the CC Discord, the link to which is here.
This is the correct place to find the latest version of the patch, and you will have access to relevant announcements and the full documentation without any further steps.
You should not download any form of Crystal Clear anywhere else, as these websites are designed to monetize you and are held to a lower standard of maintenance, and at worst have been verified to contain malicious software.
You should not buy any form of pre-made physical cartridge containing Crystal Clear online, as these are all missing key features which will actually impact the game’s performance and damage your save file.
If you want a playable physical experience, there is readily available and up-to-date information on how to assemble or obtain proper hardware in the Discord.
5+ years of supporting this project means that the Discord contains almost every imaginable answer and discussion relevant to the game, and is large enough that getting support is only a matter of time. It is actively staffed, and is the single largest gathering place for the Crystal Clear community.
I recognize the general long term instability of social media platforms, especially chat based ones. However, Discord has remained stable enough as a resource for some time now. Should that change for any reason, a replacement will be provided and the information on this page will be updated.