The second collar mounts on the front end of the top barrel to exit with the stove pipe. This allows the hot gases to go out the back top of the lower stove barrel and then circulate back through the top barrel and out the front collar affixed to the stove pipe.
You will need safe clearances above the stove for the stove pipe to snake back and out a standard chimney or install straight up from the front of the stove.
We also carry the standard steel barrel kit Click Here for more information.
Sorry not available to ship to WA, OR, and CA due to state restrictions. Installation should be completed in compliance with other state and local codes.