Undine Pure, Cosmetic Grade, Cyclopentasiloxane, also known as D5 Cyclomethicone. D5 Cyclopentasiloxane is a versatile and high-performing silicone compound ideal for cosmetic formulations. Used to enhance product spreadability and imparts a silky, lightweight texture to skin and hair care applications. As a volatile silicone, it evaporates relatively quickly leaving behind no residue, ensuring a non-reasy and smooth finish.