Flex Liner Appliance/Stove Connector?

Do I need one of these to connect my flex liner to my Harman 52i insert. I was planing on running the flex liner over the 4" stub and putting three tex screws into it.
Are there any pros or cons to using one of these. I was going to do the same thing to my fresh air intake 3" aluminum
flex pipe. It's going to cost me
$80.00 plus for the two of them if I need to use them. If not I'll
just need six screws. Ty

Hoot23 said:

If you don't use a 4" to 3" reducer it's gonna take a lot of RTV to seal that joint. I would use one. I just hooked up my in-laws stove yesterday to a flex liner. 3" out the back to a T, reducer, and liner 20' to a terra cotta plate and then a cap.

Click to expand...

Hoot23 said:

If you don't use a 4" to 3" reducer it's gonna take a lot of RTV to seal that joint. I would use one. I just hooked up my in-laws stove yesterday to a flex liner. 3" out the back to a T, reducer, and liner 20' to a terra cotta plate and then a cap.

Click to expand...

The stub coming out of the stove is for a 4" exhaust . I am going straight up the chimney and don't need any reducers or a T. The stub for the OAK which I purchased seperately from my dealer has a 3" stub for that.