We have taken in 4 stray cats over time. The first two were no problem but as soon as we added a third they started marking in our hallway. The carpet was just gross. I tried everything. Adding a 4th cat made it even worse. I cleaned and cleaned every day and it still smelled awful. I just started using this product every day and the carpet is now smell free. It is now only getting “hit” about once a day and with this product I can handle it. No smell left behind at all. The slight stains that were there even after all my previous efforts have disappeared. My life is now back in control and I don’t have to turn the poor kitty guys back outside. I was going nuts trying to get it under control...thank you for giving me my sanity back. Now I can just love my critters. I just reordered and you can expect me to be a regular customer.