I had an assembly, (may have been an older version) very similar to this product, installed on one of the mailbox types that the current instructions said wouldn't be compatible with this version. I simply added some double backed tape to the metal frame, drilled a hole in the metal tab on the flag, taped the assembly to the side of my mailbox, tied a piece of nylon boot lace in the drilled hole long enough so that it extends into the door of the mailbox so the door closes on the string and it looks and works exactly like the faded and damaged original it replaced.
I love the Mail Time flag on my mailbox.! It is so easy to see when my mail has been delivered .