​

Tick this and the back odds and lay odds on the left hand side of the betting options will be used instead of the displayed odds.

​

Example: set back odds to 1.01, tick override odds and use in an fast moving in play market such as horse racing to ensure you get matched at whatever price is available because of Betfair's "Best Execution", as the requested odds will be 1.01 (not suggesting this as a strategy though!)