For use with our HT 4" pipe this Firestop Spacer 6" Cutout plate for wall or ceiling. Measures 16" from edge to edge. 6" Diameter Center Hole Cutout . You can use one like this if you are going through a thin side wall at a 45 degree angle.https://flameinnovation.com/product/45-degree-fire-stop-spacer/

Installing through a wall with chimney pipe is tricky and care must be taken.  This is not the right part for going through a wall with a surface on the inside then insulation, and wall outside, etc.  You need an insulated wall thimble for that. Here is an article to help you pick the right parts for your installation. https://heattalk.com/how-to-install-a-wood-stove-pipe-through-wall/ Use the 4" Firestop Spacer 6" Cutout for a thin wall only where you can cut a big enough hole for clearances to combustibles.