Hat Liners

Invisible Protection. Everyday Comfort.

UPF 50+ Sundercover Signature Cap Liners

Our UPF 50+ Signature Cap Liners turn your favorite hats into powerful sun-protection gear. Engineered with lightweight, breathable fabrics, they block over 98% of harmful UVA and UVB rays—delivering the highest level of sun defense without changing your look or sacrificing comfort.

Designed to fit seamlessly inside your go-to caps and hats, our liners enhance sun-blocking performance while staying cool and barely noticeable. The Round Liner is ideal for fitted baseball caps, fedoras, bucket hats, women’s sun hats, and more—featuring an OSFM adjustable design for a secure, customized fit.

Whether you’re hitting the trails, spending a day at the beach, or heading out for everyday errands, Sundercover® cap liners provide smart, stylish protection—so you can wear the hats you love and stay protected under the sun.

Signature Hat Liners

Featured collection