The Insulated Wall Thimble is used for installation to a masonry chimney through a combustible wall. It may be used for a single wall or double wall stove pipe. The round shielding acts as a radiation shield and provides the required clearance to combustibles. Use for existing masonry chimneys or a masonry chimney which has been relined with a stainless steel liner. Allows for total wall thickness from 3.5" to 7.5".