Silvacore Pro by Duraflue liner flex to twin wall adaptor (for sitting atop a short chimney stack)When a chimney has been chopped off replace the chopped off section with twin wall. This is the lowest part. DIY article available for this project see "Somebody chopped off your stack?" onnthis page. This is a twin wall clip together chimney part used to build a new chimney. Twin wall clip together chimney can be as close as 5cm to combustible materials (7cm if passing through a sealed void). No glue or sealants required. When we say 5 or 6 we speak