Swiss pairs, leading in a weak field.
You considered opening, but systemically you probably would have had to try 2♦ Flannery, and decided against it.
1♣ is 2+ (may be balanced, but 1♦ is not strictly unbalanced).
All your 3-level bids now are natural-ish (including minor-forcing) and forcing.
4♣ is probably an auto-splinter, but no specific agreement.
Benefits include:
Plus... it's free!