Hey folks. Can you please tell me the proper name, and the best place to buy the following. One is a simple seam collar for an older double wall, 8 inch piped. The other is another, stronger collar that the long rod supports were attached to from the roof to the stack to keep the chimney in place. I'd like to know the exact terminology so I can buy some of these. Also, what's the best site to buy these from. Thanks