Several different types of these physical deterrents to FR have been available for several years, and this is after state actors employed them for their own operations. The FR industry has multiple methods to mitigate, as well as recognizes that FR is merely one biometric of many possible identification methods. The passive nature of FR is great, but it is not the only technology with passive identification capabilities. FYI, I'm at a leader in the FR industry, writing the FR applications used by many. (www.CyberExtruder.com)