The Mt. Rainier annex room is a nice addition to your Roof Top Tent. It comes with four sides and a removable pvc floor making it easy to clean. It also has an entry door, two windows and a rear entry access making it easy to get in and out of your vehicle with your tent to the side or turned off the back of your vehicle. Simply just zip it on. A great place to store extra gear, dogs or when you have those extra kids up at the lake. When open this room is approx 9'x7' at the bottom. Travel bag included.