Pictured at bottom (below standard flashing & storm collar).
The "Universal Rubber Boot Flashing" is a UL listed kit for flashing corrugated metal roofs. This is the preferred method of flashing metal roofs by installers. This metal roof pipe boot is used instead of a traditional flashing or DSA flashing and contours to the roof and created a seal around the corrugations in the roofing material. Metal roof pipe flashing kit includes: rubber boot/flashing, spacer kit, & special mounting hardware.
NOTE: This item is a "Selkirk" (Metalbestos, Super-Pro) product and is not endorsed or recommended by other brands, but is an alternative at the purchaser/installers discretion and will work on all chimneys with between 8"-10" outer diameters.