Yes! Our hats with the under brim liner have been given the highest rating of UPF 50+ for excellent UV protection. Tested in accordance with the AATCC standard 183-2014. Under brim liner offers UV-A protection of 98% and UV-B protection of 99.6%.
Our bare bottom hats do still offer great sun protection but because there isn't a liner there is more of a chance that some light can still make it through.
The visors don't have an under brim liner but because they have a tighter weave less light if any is able to pass through.