This part is listed by BMW as BMW part number 16117190947 (16-11-7-190-947) and is described as Genuine BMW Diesel Fuel Level Sensor, Left, for E90 335d (2009-2011).
This is a Genuine BMW diesel fuel pump 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:
3 Series
E90 / E91 / E92 / E93 (06-13) > 335d