How it works
With over 2.5 and under 3.5: three goals exactly — both win; any other total — one wins, one loses, and you lose only the margin gap. The bet is a cheap lottery ticket on the middle outcome.
The catch
Corridors wide enough to be profitable are rare — books quote totals tightly and the margin on both legs eats the edge. The realistic version hunts line moves: take one side early, wait for the market to shift, close the corridor at the new price.