Bad weather? Cold weather? Or just looking to get a little more privacy. Add an annex to your Aerie or Crag tent to gain so much more space. Slide the annex in the track and easily zip it up under your tent. The annex comes with a thick vinyl floor that you can zip in for more protection from the elements. The windows and the main door comes with a zip up no-see-um net. With the rear zippered access you are able to unpack in any type of weather!