Draw No Bet (DNB) removes the draw from the equation: back a side and if the match finishes level, the stake is refunded rather than lost. Only an outright defeat loses.
The price is naturally shorter than the straight 1X2 win — you're paying for insurance. It's the right tool when your analysis says one team is stronger but the draw is live: knockout ties between cautious sides, or away favourites who take a point without complaint.
DNB is mathematically identical to a 0.0 Asian handicap, and you can build it yourself by splitting a stake between the win and the draw — the packaged market just saves the arithmetic.