This is a great way to help you decide which fabric to buy and it’s simple.  Just purchase (for a nominal amount) a “see through pack of fours” emf fabric sample sets and an emf meter.  Some emf monitors like the Tenmars TM 196 come with a free “see through pack of four”. Then hold the various (labelled) emf shielding fabric pieces between your emf monitor and the high-frequency emf radiation source. Once you achieve your required reduction in emf readings on your emf meter with the relevant sample.  That’s it your emf shielding material is chosen and you know it works for your specific emf protection project.