Lewis Hamilton and Valtteri Bottas are among the eight Mercedes drivers who have opted to use their second power unit of the season.
The Mercedes pair along with McLaren drivers Daniel Ricciardo and Lando Norris, Aston Martin's Sebastian Vettel and Williams' George Russell and Nicholas Latifi have taken on a new internal combustion engine, turbocharger, MGU-K and MGU-H for Azerbaijan.
Three internal combustion engines, turbochargers, MGU-H and MGU-K can be used per driver. If four or more are used, grid penalties are awarded.
Ferrari have also decided to use Azerbaijan as an opportunity to introduce a fresh power unit so Ferrari, Haas and Alfa Romeo will run in Baku with a new engine.
Championship leader Max Verstappen is set to continue to run the power unit he has been using since the start of the season in Bahrain, although it's expected that he will use his second engine later this month.
F1 Power Unit Allowance 2021
|Power Unit part
|Internal combustion engine