4" Firestop Radiation Shield. For example, When you are passing through an attic, this is the product for you.
Required where the chimney penetrates a floor or ceiling. You can use an attic insulation shield in some instances. Depending on your install scenario. And what you want it to look like. What kind of ceiling do you have? How thick is it. 2x4 or 2x6 or not framed in at all. If you just have roof joists then you will need to build a box between them. You need support in some instances. Other products, it just needs to pass through. So it is just a barrier.
Use this type of pipe when going throughhttps://flameinnovation.com/product/4-insulated-stove-pipe-36-inch-length/
A - 6-1/8"
B - 12"
https://www.selkirkcorp.com/en/ is a great product. Safe and UL Listed. Figure out what you need and what you like the look of. When you use your 4" Firestop Radiation Shield, make sure it is secure and straight. No insulation around it up top. You can build a wood trim around the plate. This will finish it off for looks. Secure it firmly. You can hide you screws with the wood trim as well.
If you want to leave it plain. Leave it plain. This is a great, well built product.