These are compatible with Gridfinity, with the exception of the lack of magnets. The low center of gravity of the upside-down ones helps you hold top-heavy items.
The last number in the dimensions scheme indicates the height of the extra part below the base, in mm.
Note: You can put regular gridfinity on top of a Brix piece, but the nesting ones with the extended bottoms(These all have the fourth number in the filename) will probably not fit inside other bins.
These are derived from work on a previous project and haven't been tested quite as much as I'd like to see how well they fit with other Gridfinity stuff, but it seems to work really well for organizing this shelf!
The author marked this model as their own original creation.