From Halopedia, the Halo wiki
The Exchange is a rotating storefront featured in Halo: The Master Chief Collection, in which cosmetic items can be purchased with excess Season Points earned in-game. The Exchange is used as a means to reintroduce items previously only unlockable via time-limited challenges, but will also feature entirely new items that did not appear in previous seasons or their challenges. The Exchange has two categories, limited-time items which are rotated each week, and featured items, which remain available for longer. Each week, the following week's items can be previewed.
The following table lists each week's Exchange items, starting from when it was introduced on April 7, 2021.
Season 6: Raven