Arial Black 16.h Library -

const uint8_t arial_black_16Bitmaps[] = ... ; const GFXglyph arial_black_16Glyphs[] = ... ; const GFXfont arial_black_16 = ... ;

the font source code is here. as you can see in the start of the file, this is how you need to organize the data struct _FONT_ { * Arduino Forum arial black 16.h library

When you "include" this library, you are essentially embedding the font directly into the flash memory of your microcontroller. const uint8_t arial_black_16Bitmaps[] =