4" Black Ceiling Support. This support is used to support chimney from the ceiling joist. Supports up to 50 ft. of chimney. Centers chimney between floors. Round design with decorative Black hi-temp paint finish. 9" x 9" Framing Dimensions. For example, dimension A is 4" and dimension B is 9" and Dimension C is 12". Furthermore when you install this item, you get a nice finished look and clean transition of pipe. Subsequently, you can use some single wall pipe and then transition to the 4" Insulated pipe to make your install look professional as a do-it-yourselfer. 4" Black Ceiling support is about the most popular, but not your only choice. Check out our other products you can substitute in place of this item. https://flameinnovation.com/product/4-starter-box/
The choices are not limited. You can use a firestop spacer plate if you are installing in a shed with no attic space. Moreover, you can use a type of fitting where you just pass through. See our website for other high quality products.
This support does a fine job and is the best looking one that is pre-finished from the factory. It is Made in the USA. You can install the starter box and cut it to the angle of the roof and then paint it your color of choice.