An 'Elevator Pitch'.
The term ‘elevator pitch’ comes from an imagined scenario where the sales person gets into a lift, or ‘elevator’ in the States, and finds that they are alone with a very important prospect. They have a sudden unexpected occasion to sell. The prospect is trapped, but only for a very short time before the lift door opens and offers a chance for escape. So the sales person should have ready, a succinct short sales pitch that does the job. Usually it would be a 30 seconds to one minute opportunity.