Lovely antique cast iron brackets.
These are single brackets although two of them have the same measurement so could be used together for a mix & match look.
Used singly they would suit a small corner shelf or as a hook for a hanging basket
Largest 23.5 cm wide / 26cm long
2 x médium ones 18cm long / 20.5 wide
Smallest 17.5 long / 17.5 wide