Ray-Ban 2140 Wayfarer - Elle Fanning -Teen Spirit
Fanning's Wayfarer sunglasses could be the regular 2140 Wayfarer or the very similar 2130 New Wayfarer model.
Note that there are different sizes of this model, so if you buy them online, make sure to get the right size for you.
These classic Wayfarer's are one of the most popular pairs of sunglasses of all time and feature in many films.
Reference: Ray-Ban RB2140 Wayfarer, black