PUGS are Pop-Up-Gizmos. They a covering for the top of the bunkends that not only keeps the heat in during the cold weather, it helps to keep it cooler during the warmer weather. Also keeps the bunkends cleaner. There is a website. The owner is Bob and you could not ask for a more responsible, responsive and pleasant owner. Generally, he has the sizes for the various units, just needs the year, make and model. They are a reasonably priced investment and highly recommended. He has recently added an interior liner for those in really chilly climates. The material is lightweight, but does a dandy job....one side is a color and the other silver. Your choice of available colors. The vast majority of us have them and wouldn't know what to do without. Suggest checking his website.