My wife is flying this weekend and got a note from her doctor disclosing a knee replacement (so the TSA won't take her knee apart). She also has metal plates in her neck and lower back. I didn't believe her when she said the detectors won't go off with titanium, but, would with her stainless steel knee. So, I got my Pro Pointer out and sure enough, the knee sounds off, but, her neck and back didn't! I didn't try the F75, however, suspect since the PP didn't sound off, the F75 wouldn't either. Just doesn't make sense to me........I thought it would respond to any metallic object!