This part is listed by BMW as BMW part number 17127646898 (17-12-7-646-898) and is described as Genuine BMW Coolant Pipe (Expansion Tank-Cylinder Head) for F48 X1 28i (2016-2023) & F39 X2 28i (2018-2023).
Supersedes obsolete BMW part number 17122437264 (17-12-2-437-264).
This is a Genuine BMW coolant pipe with a two year warranty. Buying a Genuine part will usually be more expensive than an OEM or aftermarket brand but you are assured that it meets BMW's designs for fitment, performance, and longevity. It will also be the very latest design, incorporating any updates or revisions that an aftermarket brand typically will ignore.
BMW Fitments:
X1 Series
F48 X1 (2016-2023) > X1 28i
F48 X1 (2016-2023) > X1 28i xDrive
X2 Series
F39 X2 (2018-2023) > X2 sDrive28i FWD (18-23)
F39 X2 (2018-2023) > X2 xDrive28i (18-23)