Best Odds Guaranteed is a type of promotional bonus offered by a number of bookmakers. It does not, (confusingly!), mean that you are getting the best odds. In fact you are likely not to be getting the best odds if you are betting with Best Odds Guaranteed. What it means is that if you take an Early Price on a Horse (accept certain odds and place a money bet) then if the official odds for the horse go out and the Starting Price (Official odds at the start of the race) is higher than the odds you were given, then you will be paid out at the starting price. The Guarantee is that your odds will always be at least as good as the SP odds. It is not a guarantee that your odds will be the best available.