this is a BIG DEAL! My sink was leaking, very slowly, but it was leaking! I didn't even know about it until I discovered a pool of water in one of the plastic baskets under the sink in the closet. I had to remove all the pipes, but most importantly the exhaust/drain pipe just below the sink. During the reinstall I used Black Swan's Stay Soft Plumber's Putty and got a much better seal! Now NO LEAK! I checked everyday and it's been a week and NO LEAK! I will buy this item again!