I wore it once after purchasing it, but I'm selling it because I no longer use it. It's almost new. The RadiArmor EMF Protection Cap uses breathable silver fiber fabric that blocks over 99% of high-frequency RF and millimeter wave radiation from WiFi, cell phones, 5G communication, and more. The EMF protection lining covering the entire inside of the cap reduces high-frequency RF and millimeter waves by over 99%. The average EMF shielding rate for the head exceeds 90%. Materials: ・Outer: 100% Cotton ・Inner: 100% Inorganic fiber (silver) Size: Unisex design with an adjustable strap that fits head sizes 20-23cm (S-L size).