I am both a landlord and a realtor, this is the ONLY product I have found that actually works,and I have tried them all. I don't normally endorse products but this one really works. If you are having the work done by an outside company, I would insist on some sort of a warranty. Again, I have tried every product on the market and this is the only one I have found that works. You can also buy it online but I have had good luck finding it at discount stores as well.