It is called the hvac strap. Basically it is a bracket with a nylon strap and a super powerfull magnet on the end. They had them stuck to an outdoor unit as a display and it seemed to work well. I would use it mostly on rooftops. They said right now the only place to buy it is on their website until the supply houses picked it up. I might get one when they get to the supply house this spring when I get my yearly set of