This part is listed by BMW as BMW part number 13907636146 (13-90-7-636-146) and is described as Genuine BMW Fuel Tank Vent Valve for N20 engine on E84 X1 28i (2013-2015), F26 X4 28i (2015-2018), and E89 Z4 28i (2012-2016).
Supersedes the following obsolete BMW part numbers:
13907618641 (13-90-7-618-641)
13902366608 (13-90-2-366-608)
This is a Genuine BMW purge valve 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
E84 X1 (2013-2015) > X1 28i
E84 X1 (2013-2015) > X1 28i xDrive
X4 Series
F26 X4 (2015-2018) > X4 28i xDrive
Z Series
E89 Z4 (2009-2016) > Z4 sDrive28i