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.

Cavallari wore her shoulder-length blond hair in loose waves as a pool, blue water and distant skyline filled the background.

KRISTIN CAVALLARI ADMITS HER KIDS FLY COACH WHILE SHE SITS IN FIRST CLASS "Tan lines, vitamin C + peptides 🍍☀️," Cavallari captioned the Instagram post.

A second photo captured Cavallari from the side in the same black bikini.

The " Laguna Beach " alum leaned against the curtain with one arm raised above her head as she smiled with her eyes closed.

The pool and waterfront setting remained visible behind her.

Cavallari also used the photo shoot to spotlight a product from her Uncommon Beauty line.

In a close-up image, Cavallari leaned against a palm tree while holding a bottle of the brand’s Enhanced Pineapple Peptide Nectar near her face.

She continued wearing the black bikini as a large green leaf partially framed the photo.

The latest set of photos comes months after Cavallari stepped onto the runway at Miami Swim Week for Uncommon James’ first runway show.

During a June 23 episode of her "Let’s Be Honest" podcast, "How I Got Runway Ready for Miami Swim Week," Cavallari detailed how she prepared to walk the runway in a swimsuit.