Groundsheet for the base unit Colorado Plus frame tent made in polyester coated fabric. The Colorado, unlike the Arkansas doesn't have bigger groundsheets as the tent is expanded but instead you have to purchase another groundsheet section for each additional tent section you add. Still a heavy duty, tough wearing groundsheet but be aware that where they overlap is a weak point that could be exploited by some of the more intelligent or lucky bugs. If they do get in, please politely show them the door and ask them nicely not to come back again. Base unit groundsheet size is 400 x 590 cm, so it isn't that small or that light.