Their website(https://www.empshield.com/frequently-asked-questions/ https://www.empshield.com/frequently-asked-questions/) claims 500ps response time, which see

Their website(https://www.empshield.com/frequently-asked-questions/ https://www.empshield.com/frequently-asked-questions/) claims 500ps response time, which seems in line with MOVs(although maybe this is just a milspec test threshold so many devices will claim this response time). I wonder if you could use an MOV or similar surge suppressor in parallel with a lightning gap to achieve useful protection? As others have said, their device is not full EMP protection. At best, it will protect your electronics from a surge on the grid but not locally present EM fields. Someone should call ElectroBoom and have him do a teardown.