A middle is when two sportsbooks post different lines on the same bet, so you can take the over at the lower number and the under at the higher one. If the result lands in between, both bets win.
See today's no-lose middles ›Say one book has a player's rebounds at Over 8.5 and another has Under 10.5. Bet both. If he finishes with 9 or 10 rebounds, you win both bets. Anywhere else, one bet wins and the other loses.
Most middles cost a little when you miss, like the -$4.55 above. A no-lose middle is one where the prices are good enough that even when only one side wins, you break even or come out slightly ahead. Then the middle itself is a free shot at winning both. Those are what the middles page shows.
Betting the over at a low line and the under at a higher line on the same game or prop at two books. If the result lands between the two lines, both bets win.
A middle where the prices are good enough that you don't lose money even when only one side wins, so hitting the middle is pure upside.
It depends on the gap. A one-point gap on a points total hits rarely; a two-point gap on rebounds or assists hits more often. Each hit pays roughly double what you staked on one side.