Its great for blocking the wind or cold breeze when I have the doors slightly or completely open. I have the doors opened up a bit to reduce inside condensation. The SS1 can be closed up tight as the bottom edge is so close to the ground. But in extremely low temperatures the condensation inside can get bad. So I like the SS1 opened up to reduce any inside condensation. The solid inner allowed me to be out of the draft yet sit up and be able to look out the screen area. But I finally just used the SS1 with out an inner at all during the winter. Put the ground pad down and had my stuff sprawled around on the packed snow. I'd block the open door and breeze with gear etc. Got to the point I did not take the inner with me.
I have read that the SS1 solid inner will also fit into the SS2. But I cannot confirm this. Not sure about that.