Kristin Cavallari rocks black string bikini months after revealing runway-ready routine

Kristin Cavallari is soaking up the final stretch of summer while putting her own skin care front and center.

The 39-year-old reality star and entrepreneur wore a black string bikini in a series of new photos promoting her Uncommon Beauty skincare line.

In one of the photos, Cavallari posed beside a sheer white curtain overlooking the water while wearing a black triangle bikini with tie-side bottoms.

She stood facing the camera with one hand resting near her hip and the other holding the curtain.