I got No-Mark to try as as a last resort for our 15 year old cat who suddenly started spray marking areas in our house with pee. (A neighbor’s cat hangs around at the windows occasionally and our kitty doesn’t like it.) I have used other products that eliminate with urine odor and help stop spraying – both worked ok sort of, at least to kill the odor, but our cat did spray again. Someone suggested this so I thought I’d give it a try. So far, it seems to be working. It’s been a month with no spraying issues at all. And, our cat does appear to be a bit calmer and friendlier than he was. I am a happy camper.