Not undetectable by some humans but GREAT for elderly cats
Previously left a review as the product caused me problems with my throat when I first used it. That did pass after a week so I guess I got used to it in the air. However, my 16 year old cat had recently been having multiple fits every day and waking up out of it and biting his leg repeatedly. I am delighted to say that within 48 hours the fits stopped completely and he sleeps in a new bed on the landing beside the plug in now. He is his old laid back self, hopefully for a year or two more.