This is serious.. no, really.
This thin layer is an Electromagnetic Field Shield for iphone X, XS and similar iphones. Blocks 90% of potentially harmful EMFS and allows for safer phone handling. Made with multi-metalized fabric that puts a barrier between your phone and your body.
Simply place the EMF Skin between your phone and its case, or, peel off the backing and stick the EMF Skin on your phone. Always put your phone with eht EMF Skin facing your body when keeping your phone in your pocket.