This part is listed by BMW as BMW part number 17137889450 (17-13-7-889-450) and is described as Genuine BMW Expansion Tank for S63M engine coolant on F90 M5 (2018-2023) and F91/F92/F93 M8 (2020+).
Supersedes obsolete BMW part number 17138090271 (17-13-8-090-271).
Cap sold separately. Please see below for BimmerWorld recommended related items.
BMW Fitments:
5 Series
F90 (2018-2023) > M5 (2018-2023)
8 Series
F91 / F92 / F93 (2020+) > M8 / M8 Competition