An Omaha straight draw with many ways to hit.
When your 4 hole cards surround the board cards, you get 13–20 outs, much stronger than an OESD in Hold'em (8 outs). Example: wraps with 13, 17 and 20 outs complete by the river about 50, 60 and 70% of the time. Count only the cards that make the nuts (nut outs).