These beanies contain  EMF electromagnetic field radiation and  RF radio frequency radiation protection silver lining 

100%  sliver nylon tri-cot fabric,  cold hand wash only, non-iron, antibacterial, safe for children and mother
Fabric for blocking  av RF-signals as cell, Bluetooth, WiFi, GPS. 

Shielding Performance ： 55-70dB
Thickness: 0,2 mm

Elektric resistance against surface under 10Ω / cm, by 30-3000MHz  between 51 och 56 dB, 99.999% blockage.
Observe: 
Silver oxidation is going to occur and  the linging is going to get uneven color as yellow, black etc.