Beta Technologies shares surged more than 9% after air taxi maker Eve Air Mobility announced an up to $1 billion deal to buy motors from the Vermont-based company.

Eve, which was started by Brazilian airplane maker Embraer and is now under Eve Holding, said the manufacturing deal could equal as much as $1 billion over 10 years. The Florida-based company said it has a backlog of 2,800 vehicles.

Shares of Eve Holding gained 14%.

Eve CEO Johann Bordais called the deal a “pivotal milestone” in the advancement of the company’s electric vertical takeoff and landing, or eVTOL, technology.

“Their electric motor technology will play a critical role in powering our aircraft during cruise, supporting the maturity of our propulsion architecture as we progress toward entry into service,” he said in a release.