Spencer Barbosa has partnered with Kt by Knix on a limited-edition capsule of leakproof underwear and sleep boxers aimed at teens and young adults, the brand said. The 21-year-old social media creator, who has more than 11 million TikTok followers, will make three new colorways available on the Kt by Knix site beginning Sept. 10, 2025.
The line combines pieces from Kt by Knix — the sister brand to Knix that focuses on more affordable menstrual solutions — with designs chosen by Barbosa to emphasize comfort and reduce period stigma. The collection includes the brand’s bestselling Leakproof UltraThin No-Show Bikini in new colors and prints, plus Leakproof Luxe Modal Sleep Boxers in a printed pink that the partner called "butter-soft."
Kt by Knix said its Leakproof UltraThin No-Show Bikini has a patented leakproof strip and is made from a soft nylon mix designed to hold the equivalent of three super-sized tampons' worth of flow. The bikini three-pack is listed at $72, while the Leakproof Luxe Modal Sleep Boxer is priced at $34.
Barbosa, who has used her platform to promote body positivity, described the collaboration as a way to "say what teens are thinking" without shame or guilt. The campaign messaging emphasizes normalizing conversations about menstruation and offering practical products that blend protection with everyday wearability.
Kt by Knix launched as a more price-accessible complement to Knix, focusing on underwear and active-leaning pieces designed for people who menstruate. The company has previously marketed its leakproof underwear as an alternative to traditional menstrual products by pairing absorbent technology with familiar undergarment styles.
Retailers and brands have increasingly sought influencer partnerships to reach younger consumers; in this instance, the collaboration centers on product features and colorways selected by Barbosa rather than a celebrity-branded departure from existing designs. Kt by Knix framed the drop as a limited-time capsule and urged shoppers to buy before items sell out.
The capsule arrives as conversations about menstrual equity and period-friendly apparel continue to gain attention in fashion and health reporting. Companies selling leakproof underwear say the garments can provide backup protection, replace single-use products in some situations, or offer comfort during light to moderate flow days. Kt by Knix’s marketing highlights both functionality and aesthetics, targeting a demographic that values both practical performance and style.
The Spencer Barbosa x Kt by Knix collection will be available for purchase starting Sept. 10 on the Kt by Knix website. Pricing and availability are subject to change, and the brand is positioning the launch as a short-term release with limited quantities.