We finally purchased a home, and I got my P68 moved and going. In our previous place "professionals" installed the stove without an outside air kit. I burned it for 6 seasons that way, but wanted to get it correct when we moved. I bought a thimble that included a 2" outside air, which after installing it, I discovered the P68 requires a 3" OAK. So I bought a 3" OAK and installed that this week. I was able to reuse all of my original pellet vent pipe, and only needed to buy the thimble, the OAK, and a 45 to make the corner install successful.