Are all liner insulation kits created equal?

[EG GREV NED MIN ELD]

I have a 6" liner that I am looking to insulate.
I've seen costs from 150-250$ for a 20' blanket kit.
Anything I should look for when purchasing?

Another question. The total run of liner will be somewhere around 22', they sell the insulation in 15' or 25' lengths. Could I get away with getting a 15' and stuffing roxul in the top 3' and bottom 3' to make up the difference?

 

[mellow]

Get the 25' kit, you need to wrap the entire thing, plus it is always good to have some extra sitting around just in case, it is not like you can go to Lowes to get extra wrap.

Most kits that I have seen are the same, I got mine from rockford chimney supply and it is good quality. If you have the space in your chimney make sure you buy 1/2", that might be why you see the price difference if you are looking at 1/4".