Useless. It immediately turned pink and then disappeared. The only thing they showed was a control strip. I am unable to work and my landlord has known about it for a year and a half. I can't afford to rent out there but I want to make sure they clean it up properly and not just come and paint it over. black mold. This test turned up nothing. I have a sense of smell like a hound and my brother has almost no sense of smell and he smells when he comes in the front door and that is in my bedroom with the door closed. . Mold soils the very top of the bedroom wall, then down the wall behind the closet and onto the carpet. I want my money back.