GOOD MATIARIAL:100% Silver fibre liner.Outer layer: 100% cotton
COMFORTABLE:Lightweight and also keeps head warm when walking in cold weather.
ONE SIZE FIT ALL:The EMF hat with elasticity,suitable for all head circumference,one size fit all.
HIGH SHIELDING EFFICIENCY:Shielding Efficiency up to 99%,Proctect you head from WIF,5g,Cell Tower,Bluetooth, .etc.Shielding Efficiency will not reduce for 10 years,Easy to clean, machine washable.
TEST BY YOURSELF:Wrap your connected cell phone or WiFi tightly in your hat,the cell phone will can't be connected,and you can't get any wifi signal.