Comes with a water-resistant plastic outer cover. It can be placed on the ground to warm the pipes that run under the house's foundation, or it can be wrapped around something you want to warm, such as a fireplace. B. a water trough on a farm. I also heat concrete slabs and as far as I can tell it does it evenly. I know it was very good at heating up the concrete I poured to hold a couple of posts and it cured faster.