There are a few terminologies that’ll make you understand best odds guaranteed offers better. One such is the starting price (SP).
A starting price is simply the odds on a particular horse just before the start of the race. BOG offers only exist because starting prices exist.
Starting prices are what the bookmakers will use to determine your payout if it’s higher. You should note that sometimes, starting prices can be lower than early prices (EP).
However, since most bookmakers are paying you the “higher odds” and not the SP, you’ll get paid the EP if the SP is lower.