Why did Manchester United change its main sponsor for one game?

Why did Manchester United change its main sponsor for one game?

The "Red Devils" played against West Ham with the logo of the charitable organization RED on their jersey instead of Snapdragon.

RED is an NGO that contributes to the Global Fund, the worldwide initiative to fight AIDS, tuberculosis, and malaria in low-income countries. Together with the English club, its main sponsor, and Adidas, they will release a special edition jersey for sale, with all proceeds going to the organization.

Premier League rules state that clubs can only replace their main shirt sponsor logo for social causes, with up to three changes per season. This is the first time Manchester United has promoted an organization in this way.