Saf-T Liner come pre-drilled with pop rivets. for insulation, use Heat-Fab Saf-T Wrap – aluminum-jacketed sections of ceramic blanket that snap and lock around your pipe. You can also order 6″, 7″, and 8″ diameter 304-alloy Saf-T Liner in pre-insulated 48″ lengths. Features: Material: 304-Alloy. Economical liner for straight chimneys. Seam-welded 24-ga. stainless steel. UL Listed to 1777 Standard with 1″ clearance with Saf-T Wrap. 304-alloy has lifetime warranty for woodburning applications. Specifications: Overall Dimensions: 12″ (L) x 10″ (W).