While all sports wagers are by definition on future events, bets listed as "futures" generally have a long-term horizon measured in weeks or months; for example, a bet that a certain NFL team will win the Super Bowl for the upcoming season. Such a bet can be made before the season starts in September for the best possible payout, but futures are typically available year-round, with payouts being reduced as the season progresses and it becomes easier to predict a champion. In this example, winning bets will not pay off until the conclusion of the Super Bowl in January or February (although many of the losing bets will be clear well before then and can be closed out by the book). Odds for such a bet generally are expressed in a ratio of units paid to unit wagered. The team wagered upon might be 50–1 (or +5000) to win the Super Bowl, which means that the bet will pay 50 times the amount wagered if the team does so. In general, most sportsbooks will prefer this type of wager due to the low win-probability, and also the longer period of time in which the house holds the player's money while the bet is pending. For this same reason, most professional bettors do not prefer to place futures bets. A sportsbook may choose to buy in-play futures wagers at a price below the actual payout before a championship is decided if the potential payout is very high (and thus, damaging to the sportsbook due to the money that may be lost). The most recent example of this was when Leicester City pursued and went on to win the 2015/16 Premier League. Head-to-Head. In these bets, bettor predicts competitors results against each other and not on the overall result of the event. One example are Formula One races, where you bet on two or three drivers and their placement among the others. Sometimes you can also bet a “tie”, in which one or both drivers either have the same time, drop out, or get disqualified. Totalizators. In totalizators (sometimes called flexible-rate bets) the odds are changing in real-time according to the share of total exchange each of the possible outcomes have received taking into account the return rate of the bookmaker offering the bet. For example: If the bookmakers return percentage is 90%, 90% of the amount placed on the winning result