Lauryl PEG-9 Polydimethylsiloxyethyl Dimethicone

The snappily named Lauryl Peg-9 Polydimethylsiloxyethyl Dimethicone is a silicone emulsifier fluid whose main thing is being a good dispersant for powderssuch as mineral UV filters or color pigments. 

According to the manufacturer Kobo, this partly water- and partly oily soluble form of dimethicone helps filters like Titanium Dioxide and Zinc Oxide disperse more evenly and thus provide better UV protection while also minimizing any white-cast that often comes hand-in-hand with mineral filters.

This is why it can also be found in makeup products like eyeshadows and concealers, as it helps disperse color pigments in the same way.